Vehicular atmosphere cleansing system

ABSTRACT

A vehicular atmosphere cleansing system utilizes a regenerative wheel having flow channels extending through the wheel coated with an adsorbant. An atmosphere stream passes through a first position dependent portion of the wheel where VOC&#39;s including HC&#39;s are adsorbed while a heated atmosphere stream passes through a second position dependent regenerative portion of the wheel whereat VOC&#39;s are desorbed. The adsorbant is activated carbon having particles of micropore size adhered to the substrate by a silicone binder producing high adsorption efficiencies while withstanding relatively high regenerative heat temperatures resulting from exhaust gas sensible heat. A hydrocarbon senses HC in the desorbed heated atmosphere stream to rotatively and sequentially index pie shaped, segmented portions of the wheel into the wheel&#39;s regenerative region while also functioning as the main component of an OBD device for the system.

[0001] This invention relates generally to a system for purifying theatmosphere normally drawn into a vehicle and more particularly to asystem in which the atmosphere is cleansed of volatile organic compounds(VOC's).

BACKGROUND

[0002] It is well known to provide a vehicle with any number of airtreating systems to purify cabin air. In U.S. Pat. No. 5,667,560 toDunne, a faujasite having a specific zeolite structure is coated on arotating heat wheel. Cabin air is passed through a wheel portion whereatVOC's (volatile organic compounds) are adsorbed and the spent cabin airdehumidified whereupon it is returned as conditioned air to the cabin.The wheel rotates to another station where the adsorbed VOC's are heatedand released to the atmosphere. Generally, cabin air treating systemsare not entirely dissimilar to and bear resemblance to HVAC systems usedin stationary buildings and the like. The cabin has a set volume of airwhich can be exhausted, purified and returned in relatively small sizedunits which can be easily mounted as appendages onto the vehicle.

[0003] It is well known that a large volume of atmosphere is drawn inwhen a motor vehicle operates. In German patent DE 43 18 738C1,published Jul. 14, 1994, it is noted that 384,000 m³ of purified aircould be possible within an hour of operation of 1,000 motor vehicles.The German patent does not describe how this is possible except by somegeneral statements. However, long before the German patent, it was knownto use the vehicle, itself, as a mobile atmosphere cleansing device. Anair duct positioned on the vehicle and equipped with filters (electronicprecipitators) for cleaning the air is disclosed in U.S. Pat. No.3,738,088 to Colosimo. Colosimo mentions that a portion of the filteredair can be directed into the vehicle's carburetor. Colosimo alsomentions that a catalytic postfilter, such as of the replaceablecartridge type, can be positioned downstream of the electrostaticprecipitators to filter hydrocarbons (HC), nitrous oxides, sulphuroxides and the like. Obviously Colosimo's postfilter must adsorb orabsorb VOC's until it is saturated whereupon it is replaced.

[0004] The assignee's related PCT publications WO 96/22146 and WO97/11769 are directed to vehicular atmosphere cleansing devices anddisclose catalytic compositions for removing i) ozone or ii) ozone andCO or iii) ozone, CO and HC's from an air stream, preferably passingthrough the vehicle's radiator on which is coated the catalyticcompositions, as defined in the publications. The cleansed air isreturned to atmosphere. The references are principally directed tocatalyst compositions found effective to remove ozone, per se, orprovide oxidation capabilities to not only remove ozone but also oxidizepollutants from atmospheric air at ambient temperatures contactingvehicular surfaces at vehicle operating temperatures. However, bothreferences also mention as an alternate embodiment a pollutant treatingcatalyst composition which may comprise an activated carbon compositionthat can catalyze reduction of ozone to oxygen as well as adsorb otherpollutants. The publications also suggest the used of adsorbentcompositions to adsorb hydrocarbon (HC) and/or particulate material forlater oxidation or subsequent removal and mentions zeolites, othermolecular sieves, carbon and Group IIA alkaline earth metal oxides asadsorbers. No discussion of how the later oxidation or subsequentremoval is accomplished in an automotive environment or even ifregeneration is to be employed is made in the cited publications.

[0005] In a co-pending application, U.S. Ser. No. 09/460,924, filed Dec.24, 1999 (US00/33061), there is disclosed a 2 stage zeolite traparrangement which is sized to sequentially trap “large” HC's and then“smaller” HC's. Mixed with the zeolite is an oxidation catalyst,preferably selected from the platinum group metals. In the automotiveapplication discussed in this application, a heated stream is valvedinto contact with the zeolite to affect desorption or a rotating heatwheel with an external heating source is disclosed. In eitherarrangement, because the platinum group metal catalyst oxidizes theVOC's, the air is cleansed after leaving the catalyst and exhausted toatmosphere. While this is an effective arrangement, the expense of theplatinum group metal catalyst increases the system cost.

[0006] In another co-pending application, U.S. Ser. No. 09/391,637,filed Sep. 7, 1999 (US00/24343), there is disclosed a switchingarrangement for a VOC adsorber/desorber especially adapted forautomotive applications. The adsorber is described generally byreference to the above PCT applications to include such agents aszeolite, cordierite, active carbon, mullite or silicone carbide. Thedesorption is accomplished by switching in several disclosed ways. Inone method, an electrical resistance heater is periodically heated. Inanother way, the outlet of the ambient air being drawn into the engineis blocked by valved passages maintained at different temperatures or byair directing louvers. The VOC's recovered during the desorption switchare directed into the engine's intake manifold and subsequently cleansedby the vehicle's catalytic converter exhaust system. In the adsorptionstage the cleansed air can be emitted to atmosphere and a streamsiphoned off to the intake manifold. The engine's ECU A/F ratio is saidto be programmed to account for the periodic desorption stage andpossibly control the switch between the stages. While a number ofarrangements are disclosed in the prior application, it is generally notdesirable in a vehicular environment to effect switching an ambient airstream which has an automotive cooling function nor is it desirable,from a reliability standpoint, to have moving parts that switch airstreams or even periodically shut off and on the air streams. This priorapplication also mentions that conceptually an adsorbing wheel, a movingadsorbing strip or belt, etc in which the adsorbent means are located onor consist of a movable element can be utilized but no furtherdiscussion or showing of any such moving arrangement is disclosed. Ingeneral, the subject invention is directed to an adsorber/desorberarrangement for vehicular cleaning of the atmosphere, which avoids theexpense of an oxidizing catalyst. It also addresses the problem of VOCdisposal when the adsorber is regenerated by transferring the desorbedVOC's to the engine where the engine combustion and/or catalyticconverter on the vehicle can oxidize the emissions. It is believed thatthe fundamental approach set forth in this application represents thetype of system that can be viably commercialized. Accordingly, theinvention in this application may be viewed as an extension, refinementor improvement of the basic concepts disclosed in the invention of U.S.Ser. No. 09/391,637.

[0007] Within the emission control art for treating exhaust emissionsfrom vehicles powered by internal combustion engines, it is well knownto provide a light-off catalyst in the exhaust system near the exhaustmanifold which traps hydrocarbons (HC) during start-up of the vehicleand releases the HC for subsequent conversion by the vehicle's catalyticconverter when the engine warms up. These light-off catalysts functionas traps adsorbing the HC at low temperatures and releases them athigher temperatures whereat the catalytic converter on the vehicle iscatalytically active. Reference can be had to assignee's U.S. Pat. No.6,044,644 issued Apr. 4, 2000 to Hu et al. entitled “Close CoupledCatalyst” for a light-off catalyst and assignee's U.S. Pat. No.5,804,155 to Farrauto et al. issued Sep. 8, 1998 entitled “BasicZeolites as Hydrocarbon Traps for Diesel Oxidation Catalysts” for a HCtrap in the exhaust system.

SUMMARY OF THE INVENTION

[0008] In a general summary, this invention uses the tried and provenregenerative characteristic of a heat wheel adapted to fit theautomotive environment to effect a cleansing of the atmosphere drawninto the engine compartment of a vehicle.

[0009] In accordance with one aspect of the invention, a system forcleansing the atmosphere, including volatile organic compounds containedtherein, drawn into the engine compartment of a vehicle having aninternal combustion engine is provided which includes a rotatableregenerative heat wheel having channels extending therethrough from oneside to an opposite side of the heat wheel and the channels have acoating of activated carbon on their surface. The system generallyincludes a mechanism for directing a stream of atmosphere at enginecabin ambient temperature through a first position dependent portion ofthe heat wheel on one side of the heat wheel and a mechanism fordirecting a heated stream of atmosphere through a second positiondependent portion of the heat wheel at temperatures within the range ofapproximately 150-300° C. A mechanism for rotating the heat wheel isprovided. The activated carbon is selected to have substantially amicropore porosity, a coating density greater than about 0.5 g/in³ forsubstrates of metals, ceramics and plastics and a particle size lessthan about 25 microns which has been found able to withstand therelatively high regenerative temperatures required in the preferredapplication of the invention while attaining conversion efficiencies ofvolatile organic compound efficiencies in excess of 50%. Additionallyand somewhat surprisingly, the regeneration of the activated carbon, (ofthe stated composition which is necessary to desorb the VOC'saccumulated in the activated carbon), has been found to enhance theremoval of ozone at conversion efficiencies in excess of 50%.

[0010] In accordance with another aspect of the invention, a system isprovided for cleansing the atmosphere, including volatile organiccompounds contained therein, drawn into the engine compartment of avehicle through a forward vehicular opening having an internalcombustion engine which includes a heat wheel in the engine compartmenthaving one side defined as an entrance face surface and an opposite sidedefined as an exit face surface. A portion of the atmosphere drawn intothe engine compartment passes through a heat inlet duct which in turnhas a portion thereof in heat transfer relationship with the sensibleheat of exhaust gases emitted by the engine whereby the atmospherestream flowing through the heat inlet duct is heated from enginecompartment ambient temperatures to higher temperatures. A heat outletduct is also provided which has an entry end and an exiting end in fluidcommunication with an intake manifold of the engine. The entry end ofthe heat outlet duct is sized to correspond to the size of the exit endof the heat inlet duct and aligned to be in registry therewith. The heatwheel is positioned between the heat inlet and outlet ducts so that oneside of the heat wheel confronts the exit end of the heat inlet duct andthe opposite side of the heat wheel confronts the entry end of the heatoutlet duct. A drive for rotating the heat wheel is provided andactuated so that at any given time a first position dependent portion ofthe heat wheel is in fluid communication with a first portion of theatmosphere stream drawn through the vehicle opening whereby the firstatmosphere stream portion passes through the first position dependentportion of the heat wheel and is reintroduced back into the atmosphere.At the same time, a second position-dependent portion of the heat wheelin registry with the exiting end of the heat outlet duct and the entryend of the heat inlet duct is in fluid communication with a secondportion of the atmosphere stream drawn through the vehicle's openingwhereby the second atmosphere stream portion is heated by sensibleexhaust gas heat and passes through the second position dependentportion of the heat wheel to the heat outlet duct and into the engine'sintake manifold. The heat wheel has a plurality of channels extendingfrom one side of the heat wheel to the opposite side thereof. At leastselected channels are coated with an adsorber selected from the groupconsisting of zeolites, activated carbons, carbon molecular sieves(activated carbon being a species thereof), mesapore solids such asMobile MCM41, silica gels, silica alumina and microporous solids formedfor example, from silica, aluminum, titanium, cobalt, zinc orphosphorous besides zeolites whereby the volatile organic compounds areadsorbed in the first position dependent portion of the wheel anddesorbed in the second position dependent portion of the wheel. Thisaspect of the invention is well suited for a vehicular applicationbecause, among other things, i) an adsorber/desorber material is used toremove the VOC's thus eliminating the need for any oxidizing catalyst,such as the expensive platinum metal group catalysts heretofore requiredfor removing VOC's from the atmosphere; ii) sensible heat of the exhaustgases is used to provide the regenerative heat for the adsorber thusavoiding the expense and reliability problems associated with externalheat sources such as resistance heaters and iii) the system uses fixedheat ducts without the necessity of moving vanes, louvers or valving ofair flows to produce a highly efficient and reliable system suited tothe harsh automotive environment. While a movable baffle may be providedat the entrance of the heat inlet duct should it be desired to notactivate the system until normal engine operating conditions have beenreached or shut off the system should an engine over heat conditionproduce excessive exhaust gas temperatures, once the baffle is openedthe system is essentially steady state as described with the only movingcomponent being the heat wheel which rotates.

[0011] Because the invention lacks any valving or movable bafflescontrolling atmospheric flow while utilizing sensible exhaust gas heat,the temperature of which can vary considerably as the vehicleexperiences varying loads (such as that caused by vehicularacceleration), the adsorber is selected as a specific class of activatedcarbons which are able to withstand the high temperatures of the heatedatmosphere without disintegration while retaining its regenerativeabilities to adsorb VOC's. The activated carbon includes those carbonsas stated, which have a substantially micropore porosity, a loading onthe channels of at least about 5 g/in³ and a particle carbon size ofless than about 25 microns, preferably less than 5 microns. Importantlythe binder chosen to adhere the activated carbon to the substrate (heatwheel channel walls) has to not only withstand the high temperatures butit also cannot plasticize to a viscosity whereat the porosity of theactivated carbon is adversely affected. This invention has determinedthat a binder substantially comprising silicone in any form, such aspolymeric silicones, silica sols and silicates, is suitable for thisinventive application. Improved adhesion is obtained with siliconebinder added to carbon containing coatings which are heated to elevatedtemperatures in air. Improved adhesive results may also be obtained ifthe coating with binder, preferably a silicon latex binder, is firstheated with an inert gas, preferably nitrogen, to an elevatedtemperature to in effect carbonize the binder prior to air heating thebinder at higher temperatures.

[0012] In accordance with another aspect of the invention, a system isprovided for cleansing the atmosphere from volatile organic compoundscontained therein which is drawn into the engine compartment of avehicle having an internal combustion engine. The system includes arotatable heat wheel having channels extending therethrough and coatedwith an adsorber selected from the group consisting of zeolites, activecarbons, carbon molecular sieves, mesapore solids and micropore solids.A mechanism is provided for directing a stream of atmosphere at enginecabin ambient temperature through a first position dependent portion ofthe heat wheel on one side thereof and for directing a heated stream ofatmosphere through a second position dependent portion of the heatwheel. A heat outlet duct is provided for directing the heated stream ofatmosphere after passing through the heat wheel to the exhaust emissionsystem of the engine and a sensor in the heat outlet duct determines thepresence of hydrocarbons in the heated atmosphere for evaluating theeffectiveness of the heat wheel. In one inventive embodiment, thedesorption ability of the heat wheel is determined by a routineimplemented through a microprocessor analyzing the sensor signals toascertain whether the heat wheel has worn to the state of replacementwhereat the routine activates a warning light in the vehicle's operatorcabin in compliance with OBD (on board diagnostics) emission systemrequirements. In another inventive embodiment, the desorption ability ofthe heat wheel is utilized to cause rotation of the heat wheel throughset angular increments. In accordance with this embodiment, theinvention can control the indexing of the heat wheel by utilizing aprogrammed routine modeled as a function of time of a test or standardheat wheel to desorb a fully saturated heat wheel segment as it ages.However, in the preferred form of this inventive embodiment, aprogrammable routine comparing sensor signals over set time periods isutilized to effect indexing of the heat wheel. Significantly, theroutines are not mutually exclusive so that sensor readings can controlheat wheel rotation while also providing fail safe warnings.

[0013] In accordance with another specific inventive aspect of theinvention related to the last mentioned inventive object, the sensorselected for hydrocarbon detection is a calorimetric sensor in which oneheated channel of the sensor is provided with an oxidizing catalyst ofthe platinum metal group and its electrical resistivity compared to thatof a heated reference channel so that HC's in the ppm range present inthe atmosphere can be accurately detected to assure functioning of theheat wheel.

[0014] In accordance with another aspect of the invention, a method isprovided for cleansing the atmosphere drawn into the engine compartmentof a vehicle powered by an internal combustion engine that includes thesteps of:

[0015] a) drawing a first stream of atmosphere through a vehicularopening into the engine compartment of a vehicle by means of a fanand/or the motion of the vehicle and the first atmosphere steam is atambient engine cabin temperature;

[0016] b) drawing a second stream of atmosphere either separately fromthe first stream or split from the first stream by means of a fan and/orthe motion of the vehicle;

[0017] c) heating the second atmosphere stream by sensible heat fromexhaust gases produced by the engine to temperatures in the range ofapproximately 150 to 300° C.;

[0018] d) providing a heat wheel having channels extending therethroughfrom one side of the heat wheel to the opposite side of the heat wheeland the channels having as a coating thereon activated carbon ofsubstantially micropore porosity, a density of at least 0.5 g/in³ and amean particle size not greater than approximately 25 microns;

[0019] e) passing the first stream of atmosphere through channelsoccupying, at any given time, a first position dependent portion of theheat wheel to adsorb volatile organic compounds contained in theatmosphere;

[0020] f) passing the second stream of heated atmosphere throughchannels occupying, at any given time, a second position dependentportion of the heat wheel to desorb volatile organic compounds containedin said channels;

[0021] g) directing the second stream of heated atmosphere with volatileorganic compounds desorbed from the wheel to the gaseous emissiontreating system of the vehicle; and,

[0022] h) rotating the wheel so that before the channels in the firstposition dependent portion of the heat wheel become saturated withvolatile organic compounds they are rotated into a position whereat thechannels become channels forming the second position dependent portionof the heat wheel while the desorbed channels formerly forming thesecond position dependent portion of the heat wheel are rotated into aposition whereat the channels become part of the channels forming thefirst position dependent portion of said heat wheel.

[0023] In accordance with an implementing feature of the invention, theheat wheel is of the traditional “pancake” design with relatively shortaxially extending channels, and the wheel is divided into arcuatesegments (i.e., “pie shaped”) extending between radial lines forming aset included angle therebetween, the radial lines forming spaces betweenadjacent arcuate segments. The exit end of the heat inlet duct and theentry end of the heat outlet duct are configured to match an arcuatesegment and the heat wheel rotated incrementally, a segment at a time,to minimize heat conduction between the first and second heat wheelportions. Further, and preferably, the flow of atmosphere through thedesorbing second position dependent portion of the heat wheel can beopposite to the flow of the adsorbing first position dependent portionof the heat wheel which may promote loosening and removing particulates,among other things. Alternatively, other heat wheel configurations suchas that of a “donut” design with relatively short radially extendingchannels may be utilized or even a stationary heat wheel with rotatingheat ducts can be employed. In all instances, the heat wheel, whileregenerating the activated carbons, is not functioning as a classic heatwheel which effects heat exchange by heating heat wheel passages to ahigh temperature for subsequent reaction with a colder gas stream. Inthe present invention, the heat wheel heated segments are isolated fromthe segments in the first dependent position so that as the heatedsegment returns into the first dependent position, the activated carboncan quickly return to its adsorbing state.

[0024] In a still further inventive embodiment of the inventionutilizing the activated carbon inventive features, the heat wheel hasactivated carbon coated or deposited at the entrance end of each channelfor a discrete distance and the heat wheel has an ozone removingcatalyst, preferably MnO², deposited or coated at its exit end andextending therefrom for a discrete distance but with neither activatedcarbon nor ozone removing catalyst overlapping one another. Theactivated carbon selected for this invention is effective for removingozone at higher than 50% efficiency so that its selection as theadsorber is sufficient to not only treat VOC's but also remove ozone.Combining a known ozone conversion catalyst with the activated carbonassures high efficiencies for ozone removal from the atmosphere and itis believed the regeneration of the heat wheel extends the life of theozone removal catalyst. Still further, the sensor inventor embodiment,predicated on sensing VOC's to satisfy OBD requirements, can also beutilized to satisfy OBD ozone requirements in that a correlation betweenVOC's and ozone removal can be modeled and the programmed failurewarning routine modified to account for ozone efficiency based on thedetected efficiency of the activated carbon to remove HC's.

[0025] In general summary of the various objects, features, andadvantages of the present invention, it may be said that the inventionhas one or more or any combination of the following:

[0026] a) Stable system for vehicular atmosphere cleansing system;

[0027] b) Inexpensive;

[0028] c) High conversion efficiencies;

[0029] d) Long life;

[0030] e) VOC removal+other emissions such as ozone;

[0031] f) OBD detection;

[0032] g) Programmed operation; and,

[0033] h) Stabilized activated carbon implementation.

[0034] These and other objects, features and advantages of the inventionwill become apparent to those skilled in the art upon reading andunderstanding the Detailed Description of the Invention set forth belowtaken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The invention may take form in certain parts and in anarrangement of certain parts taken together and in conjunction with theattached drawings which form part of the invention and wherein:

[0036]FIG. 1 is a schematic plan view of a vehicular engine compartmentfitted with the atmosphere cleansing system of the present invention;

[0037]FIG. 2 is a schematic front view of a heat exchange wheel showinga portion of end views of the channels therein;

[0038]FIG. 3 is a schematic front view of the dust sections and wheelportions of the present invention;

[0039]FIG. 4 is a schematic representation of a portion of the heatwheel construction;

[0040]FIG. 5 is a schematic depiction of the channels formed in the heatwheel;

[0041]FIG. 6 is a representation of the calorimetric sensor used in theinventive system;

[0042]FIG. 7 is a graph showing the adsorption efficiency of activatedcarbon for HC as a function of its loading on a substrate;

[0043]FIG. 8 is a graph showing the effect on adsorption efficiency forHC resulting from the mean particle size of the activated carbon;

[0044]FIG. 9 is a graph showing test result traces of the auto ignitiontemperature for four different activated carbons; and,

[0045]FIG. 10 is a schematic representation of an alternative heat wheeldesign.

DETAILED DESCRIPTION OF THE INVENTION

[0046] Referring now to the drawings wherein the showings are for thepurpose of illustrating a preferred embodiment of the invention only,and not for the purpose of limiting the same, there is schematicallyportrayed in FIG. 1 a portion of a vehicle 10 shown in dash lines andincluding an engine compartment 12 and an operator cabin 14.

A) The General VOC Removal System

[0047] Vehicle 10 has one or more forward vehicular openings, designatedby reference numeral 15, which may be conventionally understood ascomprising the vehicle's grille in the preferred embodiment. Behind thegrille or forward opening 15 is the vehicle's radiator 16 and rearwardof radiator 16 is the vehicle's fan 18 powered by the vehicle's internalcombustion engine 20. For illustration purposes only, a shroud 21 isprovided between radiator 16 and engine 20 and it is understood thatthere are any number of openings (not shown) in the shroud to permitegress of the atmosphere.

[0048] As is well understood, ambient air or the atmosphere is drawn byfan 18 through grille 15, through radiator 16 and out into enginecompartment 12 after passing the blades of fan 18. As a matter ofgeneral definition and for consistent terminology when used throughoutthis specification, “atmosphere” means the outside air that we breatheand includes in addition to the standard chemical compositions(nitrogen, oxygen, and lesser amounts of carbon dioxide, argon, hydrogenetc.) trace amounts of volatile organic compounds (VOC), includinghydrocarbons (HC) such as toluene, o-xylene, hexane, benzene, methylenechloride, carbon tetrachloride etc. Also contained in the atmosphere iscarbon monoxide and ozone and any number of particulates. The atmosphereis “purified” or “cleansed” if one or more of such mentioned items isremoved or reduced or reacted into a less harmful form. This inventionis particularly concerned with removing VOC's from the atmosphere,VOC's, and more specifically HC's, are typically present in today'satmosphere, depending on location, anywhere from a “normal” of 2 ppm inurban areas to higher levels (concentrations triple normal, i.e., 6,have been reported), which can occur in highly urbanized or smog areasof the country. An “atmosphere stream” or a “stream of atmosphere” asopposed to “atmosphere” will refer to the atmosphere drawn into enginecompartment 12 by fan 18 or motion of vehicle 10 or by a combination ofvehicle motion and fan draw, which is typically the case. In theconventional vehicle 10, as described an atmosphere stream designated byarrows 25 is drawn into engine compartment 12 by fan 18 and/or motion ofvehicle 10.

[0049] In accordance with the invention a regenerated heat wheel 30 isfitted into engine compartment 12. A heat wheel is a well known devicein the art and will not be described in detail herein. It typically haspassages through which at least first and second fixed gaseous streamsat different temperatures flow. The wheel rotates so that its passagesare sequentially exposed to the gaseous streams. When the wheel isexposed to the “high” temperature gaseous stream its passages becomeheated as the hot gases flow therethrough. When the passages are rotatedinto the “low” temperature gaseous stream, the passages give up theirheat to the low temperature gas stream, thus heating the low temperaturegas stream. This invention uses a rotating, regenerative heat device toaccomplish adsorbing and desorbing VOC's as described below and thisdevice physically resembles a heat wheel. Accordingly, the device willhereafter be termed “heat wheel” but this invention does not use a heatwheel in its classic use sense as described. In fact, the use of heatwheel 30 in this invention is opposite to that of a normal heat wheeluse.

[0050] In the preferred embodiment, heat wheel 30 has a flat, pancakeshape extending from one side, defined as an entrance face surface 31 tothe opposite side, defined as an exit face surface 32. Extending betweenthe sides or face surfaces 31, 32 are a plurality of channels as shownin FIG. 2. Heat wheel 30 rotates about its center hub 35 such as by abelt 36 driven by a motor 38. The actuation and speed of motor 38 iscontrolled by a microprocessor, preferably the vehicle's ECU 40, havinga programmed routine(s), described further below, stored in ROM memoryand executed through RAM memory in a conventional manner.

[0051] A heat inlet duct schematically shown by reference numeral 42 hasan entrance end 43 in fluid communication with a portion of atmospherestream 25, and an exit end 46 confronting entrance face surface 31 ofheat wheel 30. That portion of atmosphere stream 25 flowing in heatinlet duct 42, is schematically depicted by reference arrow 26. Withinheat inlet duct 42 is a heat transfer mechanism. In accordance with thebroader scope of the invention the heat transfer mechanism can be anyheat source, such as a resistance heater. However, in accordance withspecific features of the invention, the heat source is desired to be thelatent heat of the exhaust gases produced by engine 20 for costefficiency and reliability purposes.

[0052] In accordance with this aspect of the invention, the latent heatof the exhaust gases can be utilized by simply placing a gas-to-gas heatexchanger within heat inlet duct 42. In the preferred embodiment,however, heat inlet duct 42 is constructed to form a closed channelpassing over an exhaust gas manifold 47 of engine 20. Atmosphere stream25 thus comes into contact with the exterior surface of exhaust gasmanifold 47 as it travels in heat inlet duct 42 and is heated andbecomes a heated atmosphere stream 26 and will be hereafter referred toas such throughout this description.

[0053] A heat outlet duct 50 completes the description of the fluid flowcomponents used in the system of the invention. Heat outlet duct 50 hasan entry end 51 which is shaped or configured to be substantiallyidentical with exit end 46 of heat inlet duct 42. Further, entry end 51of heat outlet duct 50 and exit end 46 of heat inlet duct 42 are alignedwith one another so as to be in registry with one another. Heat wheel 30is positioned to be between entry end 51 of heat outlet duct 50 and exitend 46 of heat inlet duct 42 so that heated atmosphere stream 26 flowsfrom heat inlet duct 42 through heat wheel 30 and into heat outlet duct50. In the preferred embodiment of the invention illustrated in FIG. 1,the direction of the flow of atmosphere stream 25 through the part ofheat wheel 30 not occupied by heat inlet and outlet ducts 42, 50, is inthe same direction as the flow of heated atmosphere stream 26. However,for better heat isolation purposes (and to assist in removal ofparticulates which may not be firmly embedded in the activated carbonduring adsorption), as will be discussed below, it is preferred that theheat streams be countercurrent one another and the preferred embodimentwill actually position heat inlet duct 42 on exit face surface 32 ofheat wheel 30 with heat outlet duct 50 confronting entrance spacesurface 31 of heat wheel 30.

[0054] Heat outlet duct 50 also has an exiting end which is in fluidcommunication with an intake manifold 53 of engine 20. Heated atmospherestream 26 in heat outlet duct 50 has VOC's present and the VOC's aretreated in the emission system provided with vehicle 10. The emissionsystem of vehicle 10 includes a catalytic converter 55. For purposes ofthis invention, it is to be understood that catalytic converter 55oxidizes certain emissions such as HC's and carbon monoxide to produce“benign” emissions while also reducing other emissions such as NOx tonitrogen and oxygen. Emission systems can be complex and can include anumber of catalysts besides catalytic converter 55, such as aclose-coupled catalyst designated generally by reference numeral 56. Byplumbing exiting end of heat outlet duct 50 into intake manifold 53, itshould be clear that the VOC's are, in the end, being purified bycatalytic converter 55. That is, the hydrocarbons present may beutilized by engine 20 as fuel during the combustion cycle of the enginebut the engine exhaust passing through catalytic converter 55 processesany VOC's not converted in engine 20. The invention, therefore,contemplates in an alternative embodiment that the exiting end of heatoutlet duct 50 can alternatively be secured to the exhaust systemupstream of catalytic converter 55, preferably, being attached (notshown) to exhaust gas manifold 47. Still further, the exiting end ofheat outlet duct 50 could be attached to both intake manifold 53 andexhaust manifold 47. In all instances, the VOC's and any other emissionspresent in heat outlet duct 50 are eventually treated by catalyticconverter 55 if not reacted sooner into harmless gaseous emissions.

B) The Heat Wheel

[0055] Referring now to FIGS. 2, 3 and 4, the general structure andsystem arrangement will be discussed. Heat wheel 30 extends radiallyoutward from an axially extending cylindrical hub 35 (which, as noted,is mounted to a rotatable shaft for rotation by motor 38) to acircumscribing band 58. Between hub 35 and outer band 58, heat wheel 30is separated into a plurality of arcuate (i.e., “pie-shaped”) segments60. In the preferred embodiment, there are 10 such segments, but in FIG.2, for drawings symmetry, there are 12 segments shown (the segments canvary in number depending on application) designated 60A-60L. Asbest-shown in FIG. 4, each arcuate segment 60 is defined by a radiallyextending leading edge wall 61 angularly spaced from a radiallyextending trailing edge wall 62. Edge walls extend axially the length ofheat wheel 30 and define pie-shaped compartments or arcuate segments60A-60L as shown. In the preferred embodiment, each arcuate or pieshaped segment extends an included angle which extends between radiallyextending edge walls 61, 62 as designated by reference letter “A” inFIG. 4. As shown in FIG. 4, there is a gap designated “B” in FIG. 4between trailing edge wall 62 of one arcuate segment (60A) and theleading edge wall 61 of an adjacent arcuate segment (60B). In theembodiment illustrated in FIG. 4, space B is shown as parallel so thatleading and trailing edges 61, 62 are not truly radial. Alternatively,gap or space “B” could be pie shaped and leading and trailing radialedges 61, 62 would then be true radial edges extending from the centerof heat wheel 30. It is preferred to minimize heat conduction effectswithin heat wheel 30, to keep gap “B” constant. Accordingly, as usedherein, “radial” means approximately radial as well as “true” radiallines extending from the center of hub 35. Gap “B” reduces includedangle “A” of each arcuate segment 60. In the preferred embodiment of 10segments, each segment would have a theoretical included angle “A” of36°, but in practice, have angles of 30-32°.

[0056] Within each arcuate segment, adsorber composition will be coatedonto the substrate as defined below. In the preferred embodiment, amonolith structure will be described which is preferred for severalreasons. However, in the broader scope of the invention, pellets,granules, or even fibrous material such as fibrous cloths or mats,coated with an adsorber composition can be utilized in the sense thateach compartment can be filled with such pellets, granules or fibers solong as the flow channels occurring between the spaces of the pellets,granules or the fibers do not give rise to a significant pressure droptending to restrict the flow of atmosphere stream 25 or heatedatmosphere stream 26 therethrough. For consistent terminology,“channels” when used herein mean any space extending through heat wheel30, no matter what its path, and includes spaces between granules orparticles, spaces within fibrous materials and formed spaces in monolithstructures as well as the spaces defined by geometric or honey combedconfigurations in monolith substrates in the preferred embodiment.

[0057] Referring now to FIG. 3, there is shown the general shape of exitend 46 of heat inlet duct 42 or entry end 51 of heat outlet duct 50which occupies one arcuate segment 60 of heat wheel 30. The large pieshaped portion remaining as shown in FIG. 3 represents what will betermed herein as a first position dependent portion of heat wheel 30 andthe small pie shaped portion designated by reference numeral 66represents what will be termed herein as the second position dependentportion of heat wheel 30. It should be clear with reference to FIGS. 2,3 and 4, that the atmosphere stream flows are into or out of plane ofthe drawing. At any given time, and as will be explained further belowwith regard to the rotation of heat wheel 30, one of the arcuatesegments 60A-60L will occupy a second position dependent portion of heatwheel 30 while all the other arcuate segments 60A-60L will occupy afirst position dependent portion of heat wheel 30. Insofar as anunderstanding of the invention is concerned, it is important to notethat atmosphere stream 25 travels through first position dependentportion 65 of heat wheel 30 while heated atmosphere stream 26 passesthrough second position dependent portion 66 of heat wheel 30. In thepreferred embodiment, the temperature of heated atmosphere stream 26passing through second dependent portion 66 will vary anywhere fromabout 150° C. to 300° C. as a result of variations in the exhaust gastemperature which will occur when the engine is placed under varyingload conditions such as when it is accelerated, climbing a hill, etc.Temperature of atmosphere stream 25 which has entered engine compartment12 will generally be considered as being at engine compartment ambienttemperature which is normally estimated at about 50° C. However, theengine compartment temperature can be anywhere from outside ambienttemperature during initial vehicle operation (i.e., in cold climates—10°C.) to higher temperatures depending on outside ambient and engineoperating conditions which can reach 120° C. and in some localized areasof engine compartment 12, as high as 140° C. Thus, the differential inheat between first dependent portion 65 and second position dependentportion 66 of heat wheel 30 can normally range anywhere from 100° C. to250° C. when the sensible heat of exhaust gasses are used as the meansfor providing the regeneration temperature for the adsorber used in heatwheel 30 and much more or much less than this under certain operatingconditions. Again, in accordance with the broader scope of the inventionan external heat source can be applied to heat inlet duct 42 to providea regeneration temperature which will not vary significantly. Thoseskilled in the art will recognize that if the variation between theregenerative temperature and the operative adsorbing temperature ismaintained relatively constant or within relatively consistenttemperature ranges, the choice of materials for the adsorber becomesless critical and the performance of heat wheel 30 can be optimized. Asnoted above, it is one of the features of the invention in the preferredembodiment to utilize exhaust gas sensible heat. It is also one of thepurposes of the invention to provide a system with minimal moving partsinsofar as controlling the flow of atmosphere streams are concerned.That is, there is no attempt to control temperature by moving or valvingatmosphere streams. The system as described ideally meets thisrequirement. There is no impediment to the flow of the atmosphere stream25 into and out of heat wheel 30 and inlet and outlet heat ducts 42, 50isolate heated atmosphere stream 26 from atmosphere stream 25 withoutthe use of baffles, valving, flow restrictors, etc. Having said this, itis recognized that a baffle may be placed at inlet end 43 of heat inletduct 42 to prevent flow of the relatively cool atmosphere stream 25 overexhaust manifold 47 until engine 20 reaches operating temperature or inthe event the engine reaches an overheat condition whereat thetemperatures of heated atmosphere stream 26 could exceed 300° C. This isoptional and does not affect the steady state operation of the systemonce engine 20 reaches normal operating temperature.

[0058] As noted, a plurality of channels axially extending the width ordepth of heat wheel 30 are formed in each arcuate segment 60, a portionof the channels shown for arcuate segment 60A, 60B in FIG. 2. In thepreferred embodiment, the channels 70 are formed in a honeycomb patternof any geometric shape and they are characterized as a “species” of“channel” by axially extending channel walls (running the width of heatwheel 30) which are joined to form a closed pattern with each wallhaving one surface defining a portion of any given channel and itsopposite surface defining a portion of an adjacent channel. Thehoneycomb pattern, desired for use in the preferred embodiment, is bestshown in FIG. 5 and includes a serpentine wall 71 sandwiched betweenarcuate walls 72 which, for drawing illustration purposes, are shown asflat but which, in fact, are slightly curved as indicated in FIG. 2. Asshown in FIG. 5, channel 70A is formed by wall surfaces of wall portions71A, 71B, 72B and 72A (although 72A is at the apex of serpentine wall71). Adjacent channel 70B is formed with the opposite wall surface ofwall portion 71B and includes wall portions 71C, 72A and 72B (72B at theapex of serpentine wall 71). Spaced along the length of serpentine wall71 is a plurality of slits or louvers 75. Louvers 75 provide fluidcommunication between adjacent channels 70 and assure contact of airstreams flowing through channel 70 with arcuate wall 72 and serpentinewalls 71. The configuration of channels 70 in the preferred embodimentrepresented in FIG. 5 is fundamentally the shape of a conventionalradiator core. Walls 71, 72 are preferred aluminum (although a ceramicor plastic material could be used) and serpentine walls 71 are of a foilgauge thickness with arcuate walls 72 slightly thicker since theyfundamentally function as a support and closure of serpentine walls 71.The channel construction generally illustrated in FIG. 5 has provenitself to be automobile durable and is lightweight. Importantly, thepressure drop of air flow through channels 70 is not significant whilelouvers 75 assure the desired air-surface contact required for thisapplication.

[0059] In accordance with the broader scope of this invention, walls 71,72 forming channels 70 are coated with any adsorbent composition capableof adsorbing VOC's, principally hydrocarbons, and which do not employ anoxidizing catalyst for reacting the hydrocarbons such as catalystsformed of the platinum group metals. The adsorbers can be selected fromthe group consisting of zeolites, cordierites, active carbons, carbonmolecular sieves (activated carbon being a species thereof), mesaporesolids such as mobile MEM41, silica gels, silica aluminum andmicroporous solids such as that formed to run from, for example, silica,aluminum, titanium, cobalt, zine or phosphorous besides zeolites.Preferred zeolites are beta zeolites and dealuminated Zeolite Y.Preferably, zeolites have a porosity sufficient to adsorb large-moleculeVOC's such as toluene, zylene, stearic acid and decanol as well assmall-molecule VOC's such as ethylene, propylene, ethanol, and acetone.In addition, the adsorbing material will adsorb particulate matter suchas particulate hydrocarbon, soot, pollen, bacteria and germs.

C) Heat Wheel Rotation and OBD

[0060] In accordance with the broader aspect of the invention,atmosphere stream 25 passes through first position dependent portion 65of heat wheel 30 where the VOC's are adsorbed as atmosphere stream 25contacts the desorbant material in channels 70. Eventually, theadsorbent composition becomes saturated with VOC's in first positiondependent portion 65 and there must be some mechanism provided fordesorbing the VOC's collected within the molecular structure of theadsorber. This is accomplished by sequentially rotating, arcuate segmentby arcuate segment 60A-60L into second position dependent portion 66 ofheat wheel 30 whereat heated atmosphere stream 26 causes, by its highertemperature, a desorption of VOC's in that segment. The desorbed VOC'sare then treated by the engine exhaust system as discussed above.

[0061] There are several factors controlling the segmented rotation ofheat wheel 30 addressed by this invention. In the normal heat transferof a classic heat wheel application, channels 70 would typically span alarger distance than one wheel segment (there would be no wheelsegments) and the channels would be heated in their second dependentposition so that heat from the channels could be given the air streamsflowing through the first dependent portion of the heat wheel. Such heattransfer arrangement could not be tolerated in the present inventionbecause if the heat in the second position dependent portion of the heatwheel is such as to cause a substantial heating of the channels 70, theheat in the serpentine and arcuate walls 71, 72 would prevent, deter orretard the ability of the adsorbing composition to adsorb VOC's when anyspecific arcuate segment 60 was rotated from the second positiondependent portion to the first position dependent portion of heat wheel30. In theory, this invention desires to heat the adsorbing material toa temperature whereat the VOC's can be desorbed without heating thesubstrate, i.e., channel walls 71, 72 so that when the regenerated butheated arcuate segment passes into the first position dependent portionof the heat wheel, it can immediately begin adsorbing VOC's. Inpractice, channel walls will be heated and the object is to avoid theheat spreading to adjacent arcuate segments and avoiding peaking oftemperatures within channel walls 71, 72. That is, serpentine walls 71are chosen as a foil and will be heated by heated atmosphere stream 26but the heat will dissipate rapidly when the heated segment is rotatedinto the first position dependent portion of the wheel. Thus, the heatisolation characteristics achieved in the invention results not onlyfrom the design of heat wheel 30 as discussed but also by the sequencingroutine used which dictates the time at which any segment remains in thesecond position dependent portion of the wheel.

[0062] Indexing the wheel at a correct time is thus critical to maintainthe wheel function not only to desorb VOC's, but also to prevent theheat from unduly interfering with the ability of the heat wheel toadsorb VOC's, i.e., permitting the heat wheel to achieve its isolationdesign affect. It is possible to model a programmed routine based upon astandard or prototype heat wheel 30. This routine can calculate an indextime based upon the time it takes to desorb a saturated arcuate segment60 of heat wheel 30 using look tables, for example, which determine orcalculate the index time based on the temperature of heated atmospheresteam 26, (also optionally and also the temperature of atmosphere stream25) and an aging factor.

[0063] While the invention can function with such a programmed routine,this invention achieves the desired indexing or timing by the provisionof a hydrocarbon sensor, specifically a calorimetric sensor 80 in heatoutlet duct 50. Calorimetric sensor 80 detects the hydrocarbons presentin heated atmosphere stream 26 after it leaves heat wheel 30.Fundamentally, when the hydrocarbons cease being detected, the wheel isindexed. However, it is to be appreciated that the hydrocarbons present(after the initial release) even in the desorbed heated atmospherestream 26 are a fraction of the hydrocarbons emitted from engine 20.Furthermore, in the normal exhaust emission system, oxygen sensors areused to control engine fueling which are more robust despite thepresence of hydrocarbon systems in the literature. It has been found,however, that a calorimetric sensor of the type disclosed herein is ableto detect hydrocarbons in the range of several ppm's. A sensor of thiscalorimetric type is able to detect the rate of change of the VOC'sdesorbed in the second heated portion 66 of wheel 30 during theregenerative cycle and it has the sensitivity necessary to determinewhen the arcuate segment has been fully desorbed. Accordingly, thisinvention uses calorimetric hydrocarbon sensor 80 to determine the timeat which the heat wheel indexes its arcuate segments into and out of thesecond position dependent portion 66 of heat wheel 30.

[0064] It also must be noted from a system concept, calorimetric sensor80 is positioned in heat outlet duct 50 to determine completion ofdesorption by failing to detect the presence of hydrocarbons. In theory,indexing control could be achieved by placing calorimetric sensor 80 inthe path of cleansed atmosphere downstream of first position dependentportion 65 of heat wheel 30 such that indexing occurs when hydrocarbonsare sensed in the air stream thus indicating adsorption saturation ofheat wheel 30. If wheel 30 is indexed on this basis, the desorption or apercentage of the desorption will float and eventually the wheel willcontinuously rotate. Importantly, it has been determined that if theadsorber is the preferred zeolites discussed above or the activatedcarbon to be discussed in detail below, the time to desorb an arcuatesegment 60 at the temperature ranges under consideration (150° C.-300°C.) is less than the time it takes for arcuate wheel segment 60 tobecome saturated with VOC's in the adsorbtion stage. It is thus aspecific feature of the invention to control the indexing of heat wheel30 by a hydrocarbon sensor, specifically calorimetric sensor 80, in heatoutlet duct 50.

[0065] In its simplest form, the programmable routine used by ECU 40 cansimply comprise the detection of an “absolute” signal value fromcalorimetric sensor 80 indicative of a set value of VOC's detected bycalorimetric sensor 80 which is a minimum value at which heat wheel 60is indexed (or alternatively the absence of any VOC's detected bycalorimetric sensor 80). By way of explanation, the desorption of theVOC's from an arcuate segment 60A-L rotated into second positiondependent portion 66 of heat wheel 30 initially results in the releaseof a large quantity of VOC's that produces a spike or a peak in thequantity of VOC's emitted and the quantity then decays or diminishes asa function of time. If a graph of VOC's desorbed over time were plotted,the trace would resemble, for example, a scintillation event detected bya photomultiplier in a nuclear camera. There would be a steep initialrise of the trace to a peak followed by an asymptotic or sine shapeddecay portion of the trace eventually leveling off at a theoreticalvalue of zero VOC's. For heat transfer, cycle time and efficiencyconsiderations, an absolute value indicative of some diminishing valuereached on the decay or tail portion of the VOC trace is selected atwhich the wheel indexes.

[0066] Another programmable routine can be utilized to compare sensorsignals over time to determine rate of change and when rate of changediminishes to a set value, indicative of some portion of the decaycurve, the wheel is indexed. For example when the tail of the tracestarts to level out, ECU 40 will signal motor 38 to index.

[0067] Yet, another programmable routine can detect the peak quantity ofdesorbed VOC's by implementing, for example, a dv/dt routine, common inscintillation event detection and then use look up tables correlated tothe peak or spike detected from which a fixed time for cycling can beextracted.

[0068] Any of the cycling programmable routines described above can beutilized in combination with fail safe routines, if desired, which canoverride the normal cycle program in the event an unusual condition issensed. For example, ECU 40 is normally supplied with exhaust gastemperature information either from sensors present in vehicle 10 orfrom programmed routines normally executed by ECU 40 to control fuelingof vehicle 10. A look-up time-temperature table can be constructed whichwill override the programmed cycle routine if a command to index heatwheel 30 is not received when a high exhaust gas temperature has beensensed for a set time.

[0069] Importantly, the calorimetric sensor can function as a device foruse in an OBD (on board diagnostic) system. Existing and contemplatedenvironmental regulations recognize that a vehicle can function tocleanse the atmosphere as well as pollute the atmosphere. Automotivemanufacturers are, or will be, given credits for vehicles which cleansethe atmosphere and those credits may be used to offset the emissionsproduced by internal combustion engine 20. Ideally, a vehicle may“cleanse” the atmosphere by an amount equal to that at which it“pollutes” the atmosphere resulting in environmentally safe vehicles.However, whatever device is used by the vehicle to cleanse theatmosphere, emission regulations provide the device must have a systemon the vehicle to sense whether the cleansing device is functioning andto signal the operator when the cleansing device is malfunctioning suchas shown by warning indicator light schematically represented in FIG. 1by reference numeral 100.

[0070] Calorimetric sensor 80 is ideally suited to accomplish thisfunction by monitoring the ability of the adsorbing material coated ontochannels 70 to release the adsorbed VOC's when channels 70 in an arcuatesegment 60A-L are rotated into a second position dependent portion 66 ofheat wheel 30. Calorimetric sensor is suited to such an applicationbecause:

[0071] 1) It has a high sensitivity to low ppm levels of hydrocarbonresulting not only from its inherent construction but also because inthe VOC application a) sensor 80 can be positioned in heat outlet duct50 at a location whereat the temperature of heated atmosphere stream 26has dropped to a low level (that is, the temperature of heatedatmosphere stream 26 is less than that of the exhaust gas applicationfor which the sensor was developed and positioning calorimetric sensor80 remote from entry end 51 of heat outlet duct 50 results in a furthertemperature drop which allows the sensor heaters, described below, toaccurately control the temperature of the sensor as described below toproduce sensitive, accurate HC readings.) and b) heated atmospherestream 26, by definition, has an excess of oxygen that is more thansufficient to provide the catalytic reactions needed by calorimetricsensor 80 to provide the sensitive readings desired and c) the flow rateof heated atmosphere stream 26, while variable, is still relativelyconstant when compared, for example, to the exhaust gas application forwhich the sensor was developed.

[0072] 2) Calorimetric sensor 80 has a rapid response resulting from theelectrical resistance signals developed by the sensor as described belowsuch that the “peak” or “spike” of the VOC trace described above can bedetected.

[0073] 3) Calorimetric sensor 80 is robust and durable because it ispositioned in heat outlet duct 50 at what is considered a lowtemperature environment and heated atmosphere stream 26, whilecontaining VOC's and other matter is not as harsh as other gaseouscompositions, for example the exhaust gases of the vehicle.

[0074] 4) Calorimetric sensor 80 is relatively speaking, an inexpensivedevice, and as indicated in the schematic of FIG. 1 is relatively simpleto implement in a system controlled by the vehicles' ECU 40.

[0075] Notwithstanding the unique characteristics of a calorimetricsensor, in accordance with the broader scope of the OBD inventiveaspects of the invention, an OBD system, using a conventionalhydrocarbon sensor, can detect a failure of heat wheel 30 using aprogrammable routine implemented by ECU 40 to actuate alarm 100. Asnoted above, when an arcuate segment 60A-L is rotated into the heated,regeneration zone a spike or peak of VOC's are released and ahydrocarbon sensor of conventional construction normally can detect thispeak. Thus the programmed routine can simply actuate warning indicator100 when peaks are not detected for “x” number of successive segments.The heat wheel 30 has failed and the failure triggers the warning asrequired. The conventional hydrocarbon sensor while capable offunctioning as a failure device would not have the sensitivity tocontrol indexing of the wheel nor could it be used to indicate how muchwear or how much life remained in the wheel.

[0076] Using calorimetric sensor 80 the failed routine can be programmedas described or the routine can be programmed to trigger a failure when“x” number of successive arcuate segments 60 fail to achieve a set levelof released HC's (absolute value) within a set time. Alternatively,failure can occur if a rate of change of signals is not within a setrange within a set time period.

[0077] Importantly, the sensitivity of calorimetric sensor 80 is suchthat a desorption trace can be recorded. A number of more sophisticatedprogrammable routines can thus be implemented by ECU 40 to determine theefficiency of heat wheel 30 as it ages. The programmable routine canintegrate the trace over a set time or the amplitude of the peak sensedor the leading edge and trailing edge of the peak differentiated. Thevalues obtained can be stored in memory and compared over time (aging)to determine efficiencies at which heat wheel is effective to adsorbVOC's. The efficiency thus obtained is relative in that the efficiencydetected is compared to that which the heat wheel had when new.

[0078] Still further, it is possible to program a routine whichdetermines an absolute efficiency based on sensor input. For example,the exhaust gas temperature can be sampled as discussed above and theatmosphere flow calculated from the airflow in intake manifold 53 and anambient temperature assumed or sensed. With these sensed parameterinputted into stored look up tables and the like in ECU40 ancharacteristic of an ideal or true VOC trace can be generated. This VOCdesorption trace (or characteristic of the trace) can be compared to thesensed, calorimetric sensor generated VOC trace (or characteristicthereof) to determine an actual sensed efficiency. If emission “credit”regulations should require an OBD system to ascertain the efficiency ofan atmosphere purification system, sensor readings from calorimetricsensor 80 can be utilized to provide such a system.

[0079] It is noted that the OBD routines and the wheel indexing routinesdescribed are not mutually exclusive. That is, one aspect of theinvention contemplates using any of the OBD routines described in anyheat wheel coated with any adsorber to assure compliance with emissionregulations requiring an atmosphere cleansing system to have a vehicularsystem advising the operator when a failure of the atmosphere cleansingsystem has occurred. Another aspect of the invention contemplates usingany of the index routines discussed above to cause accurate and timelyrotation of an atmosphere cleansing system using a heat wheel coatedwith any adsorber and using any type of OBD system to detect failure ofthe system. However, a particularly important aspect of the invention isthe use of calorimetric sensor 80 to control indexing of heat wheel 30while also providing an OBD system capable of meeting existing OBDregulations as well as contemplated OBD regulations which may occur inthe future.

[0080] The programmable routines used in the invention have beendescribed only functionally herein because it is believed, one skilledin the programming art, will not have difficulty in constructing suchroutines given the function stated above and the parameters to bemeasured and implemented as noted. Accordingly, flow charts describingthe routines further are not believed necessary to understanding andimplementing this aspect of the invention described herein.

[0081] Referring now to FIG. 6 there is generally shown in perspectiveview only a substrate portion of calorimetric sensor 80 which isbelieved sufficient to show how sensor 80 functions to generate thesignals used in the invention. Not shown is an electrochemical “oxygenpump” which is secured to and situated under the substrate shown in FIG.6. This electrochemical pump is an electrolyte such as yttriumstabilized zirconia having inner and outer electrodes so that when avoltage is placed across the electrodes, oxygen ions (resulting fromoxygen compounds in heated atmosphere stream 26) travel across theelectrodes to enter the substrate configuration disclosed in FIG. 6 andprovide oxygen for exothermic oxidation reactions. As noted above, thisis not necessary in the VOC application because heated atmosphere stream26 has excess oxygen. Also not shown in FIG. 6 is a diffusion barriersurrounding at least the top portion of the substrate illustrated inFIG. 6 which limits the amount of heated atmosphere stream 26 sensed bythe substrate but does not change the composition of the concentrationsof gaseous emissions present in heated atmosphere stream 26.

[0082] The multi layered substrate (which essentially makes upcalorimetric sensor 80) comprises a plurality of ceramic layers which,with the exception of top layer 82, supports screen-printed metalizationdefined in different patterns to form the various functional elementsnecessary to measure and control temperature within calorimetric sensor80. More specifically, top layer 82 is shown for discussion purposesonly, to have two active regions 83 a, 83 b. In one embodiment of theinvention and in one active region, a first catalyst 84 is disposed andin the other region, a second catalyst 85 is disposed. Between regions83 a and 83 b is a plurality of vias 86 through which oxygen generatedby the electrolyte discussed above diffuses. Vias 86 are present in eachone of the layers for oxygen flow to the catalysts. Immediately beneathtop layer 82 is first intermediate layer 88 which has resistancetemperature devices (RTDs) 89 a, 89 b underlying active regions 83 a, 83b respectively. Underlying first intermediate layer 88 is a secondintermediate layer 91 which contains resistance heating elements 92 a,92 b underlying first and second active regions 83 a, 83 b respectivelywhich will hereafter be termed compensation heater 92. A thirdintermediate spacer element 93 is provided and underneath thirdintermediate layer 93 there is a fourth intermediate layer 95 containinga primary heating element 96 and a fifth or bottom layer 98 alsocontaining a primary heating element 99.

[0083] In operation, voltage is applied to primary heating elements 96,99 to bring calorimetric sensor 80 to a predetermined stable temperatureas measured by one of the RTDs 89 a or 89 b. As exothermic reactionsdevelop on catalyst surfaces 84, 85 different temperature risesoccurring over regions 83 a, 83 b will be sensed by RTDs 89 a, 89 b. Tocompensate for the rises detected by RTD's 89 a, 89 b, an appliedvoltage will be supplied (actually reduced) compensation heaters 92 a,92 b to bring RTD readings 89 a, 89 b into balance. This poweradjustment necessary to return RTDs 89 a, 89 b to equal resistances(temperatures) is proportional to the difference in the exothermicoxidation heat generated by the reactions promoted vis-a-vis catalysts84, 85. Reference should be had to U.S. patent application Ser. No.08/970,837, Filed Nov. 14, 1997, entitled “Calorimetric Hydrocarbon GasSensor” for a detailed description and showing of the specific circuitryutilized to raise the temperature to bring active regions 83 a, 83 binto balance with one another.

[0084] Standard practice is to apply a non-reactive type catalyst to oneof the active regions 83 a, 83 b and which functions as a referencesignal while an active catalyst is applied to the other active region 83a or 83 b. As to the composition of the catalyst for first and secondcatalyst 84, 85, reference should be had to U.S. patent application Ser.No. 08/970,259, filed Nov. 14, 1997, entitled “Exhaust Gas Sensor” whichdefines a number of catalyst compositions which can be utilized topromote selected exothermic oxidation reactions. Insofar as the heatwheel application is concerned, one area 83 a or 83 b could be coatedwith a CMS (carbon monoxide selective) selective catalyst and the otherarea 83 b or 83 a could be coated with a catalyst capable of sensing allcombustibles (HC, CO, H²) such as a platinum rhodium catalystimpregnated into a prestabilized alumina. Subtracting the totalcombustibles signal from the COS catalyst signal yields an HC signal.Preferred, however, is to simply coat one area, 83 a or 83 b with acatalyst capable of detecting all combustibles and leaving the otherarea, 83 b or 83, uncoated or coated with a non-reactive material. Theselective gas differentiation ability of calorimetric sensor 80 ismentioned should governmental regulations require detection of aspecific gas. In such event, the programmable routines used with thesensor can give total combustibles as well as gas specific readings.

[0085] Insofar as the total combustibles catalyst is concerned, acatalyst 84 applied to active region 83 a comprises active metalcomponents such as one or more of the following elements: platinum,rhodium, palladium, iridium, and ruthenium. Generally, platinum, rhodiumand palladium are preferred. These active metals are preferablysupported on a stable refractory support such as alumina, zirconia,titania, silica, silica alumina or other similar ceramic materials. Highsurface area materials such as gamma alumina are preferred. Optionally,an oxygen storage material such as ceria may be added to the catalystformulation. However, this material is not essential because heatedatmosphere stream 26 has more than sufficient air or oxygen. Thus, evenmore preferred are refractory materials that are especially stabilizedby thermal, geothermal or chemical means, such as precalcined aluminaand ceria stabilized zirconia. The particle size of the catalyst shouldbe such that a binder can be used to adhere the catalyst formulation. Inaddition, the particle size and uniformity of the catalyst should besuch that the processes for catalyst deposition, such as screenprinting, are feasible. In general, the mean particle size of thecatalyst material should be less than ten microns in diameter with amore or less normal distribution about that mean. More preferred is amean particle size of approximately 5 microns in diameter.

D) The Adsorber

[0086] D1) The Activated Carbon.

[0087] A particularly important aspect of this invention is theselection of activated carbon within the ranges discussed below as theadsorber for a vehicular atmosphere cleansing system. Activated carbonis a microcrystalline, nongraphitic form of carbon, which has beenprocessed to increase internal porosity. It is typically formed bythermal activation processes performed on carbonaceous materials such ascoal, coconut shells or by the use of chemical activation agents,typically phosphoric acid, on materials such as saw dust in a kiln atelevated temperature. This invention is not limited to activated carbonmade by any specific process.

[0088] Generally, the larger the surface area of the activated carbon,the greater its adsorption capacity. The available surface area ofactivated carbon is dependent on its pore volume. Since the surface areaper unit volume decreases as individual pore size increases, largesurface area is maximized by maximizing the number of pores of verysmall dimensions and/or minimizing the number of pores of very largedimensions. Pore sizes are defined by the International Union of Pureand Applied Chemistry as micropores (pore width<1.3 nm), mesopores (porewidth=1.8-50 nm), and macropores (pore width>50 nm). Micropores andmesopores contribute to the adsorptive capacity of the activated carbon;whereas, the macropores reduce the density and can be detrimental to theadsorbant effectiveness of the activated carbon, on a carbon volumebasis. The adsorption capacity and rate of adsorption depend to a largeextent upon the internal surface area and pore size distribution. Thisinvention is limited to activated carbon having pore sizes defined assubstantially micropores. Substantially micropore porosity means about amajority of the pore size, approximately 50% or better, have microporeporosity. While definitive testing has not been conducted, it isbelieved, based on the activated carbon samples which have given goodtesting results, that about 50% of the porosity is of micropore size,about 40% is of macropore size and the balance, about 10%, is ofmesapore size. It is preferred that porosity of the activated carbonwhich does not comprise micropore size be substantially, or in excess of50%, macropore size.

[0089] The function of the inventive system is to removehydrocarbons/VOC's (HC) from ambient air. The HC's typically found inambient air consist mostly of alkanes, alkenes and aromatics. Theremoval of these materials from the air is accomplished by use of anadsorbent. The adsorbent functions in the following manner. Theadsorbent removes HC's from ambient air that passes over the adsorbent.The HC's are retained on the adsorbent until the temperature is raisedsignificantly. Upon raising the temperature, the previously adsorbedhydrocarbons are desorbed and channeled to a collection device thatroutes them to the engine air intake. Preferably, the collection deviceis a duct, such as heat outlet duct 50 described above. The HC's arethen mixed with fuel and burned in the engine.

[0090] The adsorbent is supported on a suitable substrate, which is amechanical device of high geometric surface area that can allow largevolumes of air per unit time to pass through the substrate. Thissubstrate must be able to withstand, without failure, the temperatureswing necessary for adsorption and desorption. This device must have arelatively low pressure drop and be compatible with the other elementsof the automobile design. One design for the substrate is a porous wheeldescribed as heat wheel 30 discussed above. To desorb the retained HCall or part of the wheel must be heated at certain time intervals. Ifonly a portion of the wheel is heated at one time in a regenerationsection, then the wheel must rotate so that over a period of time theentire wheel experiences an elevated temperature. Alternatively theregeneration hardware (heat inlet and outlet ducts 42, 50) must move todifferent sections of the wheel. Normally it is more convenient to havethe wheel rotate.

[0091] Thus the net effect is that the adsorbent is coated on a poroussubstrate through which large volumes of ambient air are passed. Theporous substrate is located under the hood in the engine compartment.The temperature of the air under the hood is likely to be in thevicinity of 50° C. due to heat from the engine and other equipment inthe car. After a certain period of time, based on the sorbent capacity,the temperature, the concentration of hydrocarbons in ambient air andother factors, the adsorbent becomes saturated or nearly saturated andis ready for regeneration. A section of the wheel rotates into theregeneration area. Hot air is supplied to this section in order to drivethe adsorbed HC off the sorbent. The flow of this regeneration air canbe co-current or counter current to the adsorptive flow. It is preferredthat the flow be counter current. The required heat can be obtained fromany convenient source such as the engine exhaust or an external heatingdevice. The temperature used to desorb the hydrocarbons depends on theadsorbent type, the type of HC adsorbed, the available heat source etc.However, the temperature will generally be in the range of 150 to 300°C.

[0092] Thus the process involves adsorption of HC at approximately 50°C. and desorption of HC at approximately 200° C. These process stepsalternate as the device is used.

[0093] In order to simulate this process conveniently in the laboratory,a laboratory test reactor was built which reasonably mimics the processto which the sorbent would be exposed. This consists of an adsorptionstep where a small piece of substrate coated with an adsorbent is heatedto 50° C. and exposed to ppm concentrations of hydrocarbon(s) such ashexane, hexene or toluene (i.e., alkane, alkene and aromatic). Enoughwater is added to keep the humidity at about 50% (relative). After acertain period of time the temperature of the substrate is raised to180-200° C. This increase in temperature results in desorption ofadsorbed hydrocarbons during a regeneration step. The temperature isthen reduced and the adsorption/desorption cycle is repeated as needed.

[0094] The test reactor consisted of a quartz tube containing acylindrical ceramic monolith (400 cpsi) dimensions ¾″ (diameter)×1″(height) or alternatively a small section of an automobile radiator ¾″(width)×½″ (height)×¾″ (depth). The substrate was coated with a sorbentto a level of approximately 1g/in3 (of substrate volume) or less. Thesesubstrates give little or no pressure drop. The tube was placed in atube furnace which supplied heat on demand. Gas containing known ppmlevels of one or more representative hydrocarbons was passed over thesubstrate at space velocities (airflow rate in cc/hr divided by thevolume of substrate in cc) and are similar to those expected on asorbent wheel that would be on an automobile. The gas exiting from thesubstrate was routed to a hydrocarbon analyzer that was monitoredcontinuously. A thermocouple was placed at the inlet face of thesubstrate. This allowed an ability to monitor the gas temperature andcontrol the tube furnace. The experiment consisted of flowing gascontaining no hydrocarbon over the coated substrate while the substrateand the gas were heated to 50° C. Then hydrocarbon was then introducedto the gas flow using calibrated mass flow controllers and analyzed gasmixtures. The HC gas was fed to the substrate for 30 min. Then thetemperature was raised to 200° C. Although the HC flow continued, HC'swere desorbed from the substrate. After a period of time, thetemperature was cooled to 50° C. without HC flow. The adsorption anddesorption cycle can be repeated as necessary.

[0095] From the known concentration of feed HC and the exitconcentrations one can calculate the amount of HC picked up during theadsorption phase and the amount of HC released during the desorptionphase. The variables reported for the experiment are the following:

[0096] HC used in feed (e.g., toluene, hexane, and hexene)

[0097] 1) Concentration of HC in feed—(ppm as C1)

[0098] 2) Size and type of substrate

[0099] 3) Adsorbent type

[0100] 4) Adsorbent coating level (g/in3)

[0101] 5) Adsorption temperature (° C.)

[0102] 6) Adsorption time (min)

[0103] 7) Desorption temperature (° C.)

[0104] 8) Temperature ramp rate (° C./min)

[0105] 10) Time at desorption temperature (min)

[0106] 11) % HC adsorbed (100★amount adsorbed/amount fed)

[0107] 12) % HC desorbed (100★amount desorbed/amount adsorbed)

[0108] 13) Number of cycles.

[0109] This laboratory test gives a reasonable approximation to theperformance expected by an adsorbent used on a wheel.

EXAMPLE 1

[0110] This example is a control experiment demonstrating that anadsorbent is needed for adsorption of hydrocarbon and that the substratehas no adsorptive activity.

[0111] A blank monolith with no coating (i.e., no adsorbent) was placedin the reactor and heated to 50° C. Approximately 5 ppm of toluene wasfed to the reactor. No adsorption was observed. The same result occurredwhen a radiator minicore was used (i.e., no adsorption was observed):Variable Units Hydrocarbon Toluene [HC] ppm C1 5 Substrate Monolith orMinicore Adsorbent None Loading G/in3 0 Adsorption ° C. 50 Temp.Adsorption Time Minutes 30 Desorption Temp ° C. NA Desorption TimeMinutes NA Temperature ° C./min NA Ramp # of Cycles 1 % HC Adsorbed 0 %HC Desorbed NA

EXAMPLE 2

[0112] In this experiment beta zeolite was coated onto a standardmonolith. The results are shown below. Variable Units ResultsHydrocarbon Toluene [HC] ppm C1 4.43 Substrate Monolith AdsorbentZeolite Beta Loading g/in3 1.06 Adsorption ° C. 50 Temp. Adsorption TimeMinutes 30 Desorption Temp ° C. 200 Desorption Time Minutes 30Temperature ° C./min 10 Ramp # of Cycles 2 % HC Adsorbed 27 % HCDesorbed 98

EXAMPLE 3

[0113] A aluminum minicore coated with activated carbon (Kreha PW) wastested for toluene adsorption. Results are contained in the table below.Variable Units Results Hydrocarbon toluene [HC] ppm C1 5.06 SubstrateMinicore Adsorbent Activated Carbon Loading g/in3 0.54 Adsorption ° C.50 Temp. Adsorption Time Minutes 30 Desorption Temp ° C. 200 DesorptionTime Minutes 30 Temperature ° C./min 10 Ramp # of Cycles 2 % HC Adsorbed39 % HC Desorbed 100

[0114] Although the substrates are different, the activated carbon inthis example shows a higher adsorption percentage than that achievedwith the zeolite in Example 2.

[0115] This coated minicore was also tested for ozone destruction atthree temperatures (75, 50 and 25° C.). The inlet ozone concentrationwas 250-290 ppb. The dew point of the inlet air stream was 15° C. Thetable below shows the results. Space Velocity Ozone Temperature (° C.)(hr −1) Conversion (%) 25 400,000 45 25 800,000 31 50 400,000 59 50800,000 44 75 400,000 63 75 800,000 48

[0116] Thus the activated carbon adsorbs hydrocarbons as well asdestroys ozone. It is a dual function system.

[0117] Some additional comments are believed in order with respect tothe destruction of ozone. The tests measured the ozone present which wasinputted to the coated minicore and the ozone present in the atmospherestream which left the minicore. The values quoted in the table aboverepresent the difference. It is possible the ozone was catalyzed andreduced to 0² or the ozone was adsorbed onto the activated carbon. Testswere run at different temperatures and the percentages representing“before” and “after” differences was relatively constant. This indicatedthat the ozone was catalyzed. If the ozone was adsorbed, lesserpercentages would be recorded as the temperature increased. It isbelieved the activated carbon is functioning to both catalyze and adsorbthe ozone, although testing has not been conducted as of the date hereofto verify this conclusion. For purposes of this invention, it isbelieved sufficient to note that the preceding table shows the inventionis sufficient to remove ozone from the atmosphere.

EXAMPLE 4

[0118] The following example illustrates that alkanes can be adsorbedand desorbed from activated carbon (Carbochem CA-10) Variable UnitsResults Hydrocarbon Hexane [HC] ppm C1 4.05 Substrate Ceramic MonolithAdsorbent Activated carbon (Carbochem CA-10) Loading g/in3 1.0Adsorption ° C. 50 Temp. Adsorption Time Minutes 30 Desorption Temp ° C.200 Desorption Time Minutes 30 Temperature ° C./min 10 Ramp # of Cycles3 % HC Adsorbed 33 % HC Desorbed 100

EXAMPLE 5

[0119] This example illustrates that aromatics can be adsorbed anddesorbed using activated carbons (SA-30) Variable Units ResultsHydrocarbon toluene [HC] ppm C1 5.10 Substrate Ceramic MonolithAdsorbent Activated carbon Loading g/in3 1.17 Adsorption ° C. 50 Temp.Adsorption Time Minutes 30 Desorption Temp ° C. 200 Desorption TimeMinutes 30 Temperature ° C./min 10 Ramp # of Cycles 2 % HC Adsorbed 68 %HC Desorbed 94 (2^(nd) cycle)

EXAMPLE 6

[0120] This example illustrates that adsorption of HC is proportional toloading. A ceramic monolith was coated with carbon at several differentloadings (i.e., grams of coating per unit volume of ceramic monolithsubstrate) and the % adsorption of toluene was determined by the methodsdescribed in the previous examples. The results for carbon PC-1 areshown as a plot of adsorption vs loading in the graph depicted in FIG.7. The graph shows that the relationship is linear for activated carbon.The substrate for the activated carbon coating shown in FIG. 7 wascordierite having 400 cells/square inch. The substrate affects thecarbon loading. Generally speaking, the more porous the substrate, thehigher the loading of activated carbon which can be placed in thesubstrate until no further improvement in adsorption efficiency isdetected, neglecting, for purposes of this statement, any considerationof the binder. Testing was not conducted for the cordierite substrate toshow the position whereat further loading will not increase theadsorption efficiency. However, this limit for the aluminum foilapplication has been observed to occur at about 0.6 g/in³. As notedabove, the substrates suitable for vehicular application include metals,plastics and ceramics. Accordingly, a minimum loading resulting inacceptable adsorption efficiencies for all applicable substrates isabout 0.5 g/in³. Optimum loadings will vary depending on several factorsincluding mean particle size, porosity, the binder and the substratechosen.

EXAMPLE 7

[0121] This example illustrates that the particle size of the activatedcarbon affects the degree of adsorption of hydrocarbons. Carbon A had anas-received mean particle size of approximately 14 microns. Thismaterial was coated onto a monolith at several loadings and theadsorption of toluene was determined by the methods describedpreviously. Carbon A was then milled in water. The mean particle sizewas reduced to approximately 5 microns. This reduced size material wasthen coated onto a monolith and adsorption of toluene was determined bythe method described previously. As shown in FIG. 8, there is a greateradsorption for toulene than the unreduced particle size carbon. Thetrace illustrated by the upper curve designated by reference numeral 110shows the adsorption efficiency for the activated carbon milled to 5microns whereas the trace illustrated by the lower curve designated byreference numeral 111 shows the adsorption efficiency for the activatedcarbon having a mean particle diameter of approximately 14 microns.Preferably, an activated carbon mean particle size should not be greaterthan about 25 microns to achieve meaningful adsorption efficiencies,more preferably not greater than about 10 microns and most preferablynot greater than about 5 microns. As a result, adsorption efficienciesin excess of 50% for the loading ranges discussed can be achieved for anatmosphere containing 2 to 6 ppm VOC and/or HC.

EXAMPLE 8

[0122] The activated carbon selected must be thermally stable under thetemperature ranges discussed. Thermogravimetric analysis can be used todetermine the ignition temperature of carbons. In this experiment, asmall amount of the carbon is placed in the balance of the apparatus.This balance determines the weight of the carbon during the experiment.The temperature of the carbon is raised from room temperature to 1000°C. in air at a fixed rate (e.g. 20° C./minute). The weight of the carboncan then be plotted as a function of temperature. When the temperatureof the carbon is sufficient to give ignition or burning, the carbon isoxidized to gaseous CO₂. As a result, the weight of the carbon isreduced. In practice when this ignition occurs a rapid loss of weight isobserved.

[0123] Typically, when the temperature of a carbon is raised to 100° C.,desorption of adsorbed water occurs. The weight of the carbon thenremains constant as the temperature is raised until ignition occurs. Atthis point a dramatic loss in carbon weight is observed. The point atwhich this dramatic weight loss occurs is the ignition point.

[0124] For the subject application, it is important that the carbon doesnot burn at regeneration temperatures, i.e. the ignition temperature isbelow the maximum regeneration temperature. For the subject invention,the ignition temperature is higher than 300° C. An even higher ignitiontemperature is preferred.

[0125] Shown in FIG. 9 are TGA test results for four commerciallyavailable carbons. The tests results for each are shown as tracesindicated by reference numerals 120 (Kreha Pw), 121 (Acticarbone), 122(Carbon “A”) and 123 (Carbchem SA30-1). Clearly there is a range ofignition temperatures from about 350° C. to about 650° C. Differentcarbons have different ignition temperatures depending on a number offactors such as carbon to hydrogen C/H ratio, degree of activation,morphology etc. This invention does not set limits for such factors todetermine a satisfactory auto ignition temperature of the selectedcarbons. It is believed sufficient to note that the activated carbonselected must have an auto ignition temperature in excess of the upperlimits of the potential operating temperature of the system and suchactivated carbons can be obtained from commercial suppliers ifspecified. It is noted that because of the potential for the carbon toauto ignite and deteriorate at higher temperatures such as shown in FIG.9, the adsorbent wheel system of the present invention discussed abovemay have an optional routine for monitoring the exhaust gas temperatureand thus for indexing the wheel in a temperature override situation.Additionally, the system may have, as an option, a baffle at inlet end43 of heat inlet duct 42 which could be actuated (not shown) to open orclose flow of atmosphere stream 25 into heat inlet duct 42 (thus formingheated atmosphere stream 26). If a potentially damaging high exhaust gascondition occurred, the actuator for heat inlet duct 42 would be closed.

[0126] D2) The Binder.

[0127] Although organic polymer binders (such as acrylic latex binders)find extensive use in the architectural paint industry, their use forother applications is limited by the maximum use temperature of thespecific application. In general, acrylic latex type organic polymerbinders are not suitable for use at temperatures above 150° C. since thepolymer degrades and thereby loses its adhesive and binding capability.For applications that require binding at temperatures in excess of 150°C., the use of silicone polymers is one alternative. For example,silicone polymers find use as binding aids for coatings applied tosmokestacks or automobile mufflers that can reach several hundreddegrees Celsius in normal application. Although the organic portion(e.g. the methyl and phenyl groups) of the silicone polymer will degradeat high temperature, the Si—O network of the polymer molecule remains.This network of inorganic (Si—O—Si—O)_(x) polymer helps to providebinding for coatings at high temperature.

[0128] Research has shown that incorporation of polymeric siliconebinders into carbon-containing slurries substantially improves theadhesion of coatings derived therefrom after high temperature heattreatment of the coatings. Further, it has been found that heat treatingcarbon coatings containing silicone latex binder under nitrogen at 200°C. (i.e. “carbonizing” the coating) prior to high temperature exposurein air provides an additional improvement to the coating adhesion.Finally, addition of other inorganic silicone containing materials suchas sodium silicate and silica sols has been shown to improve coatingadhesion as well.

EXAMPLE 9

[0129] A carbon-containing slurry was prepared by first milling 250 g ofKreha PW carbon (lot # 97020) in 375 g of DI water using a ball mill. Toaid in the milling process, 30 g of Tamol 165A dispersant (25% solidssolution; 3% solids basis relative to carbon solids) was added. Periodicdropwise additions of Rhodoline 999 defoaming agent were also requiredto eliminate the buildup of foam in the milled slurry. The carbon wasmilled for a total of 74 hours to a median particle size of 4 um(90%<6.6 um). 100 g of the resulting milled slurry was combined with7.02 g of Attagel 50 suspension aid (13% solids solution; 5% solidsbasis relative to carbon solids), 7.30 g of P-376 acrylic latex binder(50% solids dispersion; 20% solids basis relative to carbon solids),0.09 g of BC-720 wetting agent (99.5% solids solution; 0.5% solids basisrelative to carbon solids), and 0.11 g of Nuosept 95 preservative (50%solids solution; 0.29% solids basis relative to carbon solids). TheTamol 165A dispersing aid and the P-376 latex binder were purchased fromRohm & Haas; the Rhodoline 999 defoaming agent and the BC-720 wettingagent were purchased from Rhodia; the Attagel 50 suspension aid wasobtained from Engelhard Corporation; and the Nuosept 95 preservative waspurchased from Huls Creanova.

[0130] The carbon slurry prepared above was coated onto two small pieces(minicores) of Volvo S80 high performance radiator (80 fins/dm; 1.5″deep). The loading of dry coating on each was about 0.5 g/in³ ofradiator minicore volume. After drying at 90° C. for approximately 30minutes, the coated minicores were heated to 300° C. in air forapproximately 2 hours. After this high temperature treatment, theminicores were then subjected to adhesion testing. This was accomplishedby ultrasonicating the samples in water for 5 minutes at a power settingof 6 using a Crest variable power ultrasonic bath (model 4HT-710-3-ST).After ultrasonication, the samples were dried at 90° C., and the carboncoating weight loss for each due to ultrasonication was calculated. Inthis case, the average weight loss for both samples was very high (84%).

EXAMPLE 10

[0131] A carbon slurry was prepared according to the procedure outlinedin Example 9 except that only 3.64 g of P-376 binder (50% solidsdispersion; 10% solids basis relative to carbon solids) were added. Inaddition, 3.64 g of Silres M-50E silicone latex binder (50% solidsdispersion; 10% solids basis relative to carbon solids) were added. TheSilres M-50E binder was purchased from Wacker Chemie.

[0132] Coating and adhesion testing of radiator minicores using theslurry containing silicone polymer binder was accomplished as describedin Example 9. In this case the average coating loss for the two sampleswas only 4%. Clearly, the M-50E silicone binder provided excellentadhesion for the carbon coating after high temperature exposure (4 vs.84% coating loss).

EXAMPLE 11

[0133] A ceramic minicore sample coated with the silicone latex bindercontaining slurry prepared in Example 10 was evaluated for adsorptionand desorption of toluene in a laboratory reactor as discussed above.The test results indicated that after heat treatment to 300° C., thesample had excellent adsorption and desorption properties and removed62% of the toluene from the reactor inlet stream.

EXAMPLE 12

[0134] A carbon slurry was prepared according to the general procedureoutlined in Example 9 (4 um median particle size after milling) exceptthat SA-30 brand carbon from CarboChem was used instead of the Kreha PWcarbon. Additionally, 5% Tamol 165A dispersant (solids basis relative tocarbon solids) was added to the slurry instead of just 3%. Coating andadhesion testing of radiator minicores was accomplished as described inExample A. Again, the average coating loss for the two samples was veryhigh (77%).

EXAMPLE 13

[0135] A carbon slurry was prepared according to the general procedureoutlined in Example 10 (4 um median particle size after milling) exceptthat SA-30 carbon from CarboChem was used instead of the Kreha PWcarbon. Additionally, 5% Tamol 165A dispersant (solids basis relative tocarbon solids) was added to the slurry instead of just 3%. Coating andadhesion testing of radiator minicores was accomplished as described inExample 9. In this case the average coating loss for the two samples was36%. Again, inclusion of the M-50E silicone latex binder into the SA-30carbon slurry provided significantly improved adhesion for the carboncoating after high temperature exposure (36 vs. 77% coating loss).

EXAMPLE 14

[0136] A ceramic minicore sample coated with the silicone latex bindercontaining slurry prepared in Example 13 was evaluated for adsorptionand desorption of toluene in a laboratory reactor according to theprocedure outlined previously. The test results indicated that afterheat treatment to 300° C., the sample had excellent adsorption anddesorption properties and removed 64% of the toluene from the reactorinlet stream.

EXAMPLE 15

[0137] A carbon slurry was prepared according to the general procedureoutlined in Example 10 (3 um median particle size after milling) exceptthat SA-30 carbon from CarboChem was used instead of the Kreha PWcarbon. Additionally, 5% Tamol 165A dispersant (solids basis relative tocarbon solids) was added to the slurry instead of just 3%, and 10%Nalco-Brand sodium silicate binder (solids basis relative to carbonsolids) was also added. Coating and adhesion testing of radiatorminicores was accomplished as described in Example 9, and averagecoating loss for the two samples was 23%. In this case, inclusion of theNalco-Brand sodium silicate to the SA-30 carbon slurry provided furtherimprovement to the coating adhesion after high temperature exposurebeyond that seen with only the silicone binder (23 vs. 36% coatingloss).

EXAMPLE 16

[0138] A carbon slurry was prepared according to the general procedureoutlined in Example 10 (3 um median particle size after milling) exceptthat SA-30 carbon from CarboChem was used instead of the Kreha PWcarbon. Additionally, 5% Tamol 165A dispersant (solids basis relative tocarbon solids) was added to the slurry instead of just 3%, and 10% Nalco2327 silica sol binder (solids basis relative to carbon solids) was alsoadded. Coating and adhesion testing of radiator minicores wasaccomplished as described in Example 9, and average coating loss for thetwo samples was 27%. In this case, addition of the Nalco silica sol tothe SA-30 carbon slurry provided further improvement to the coatingadhesion after high temperature exposure beyond that seen with only thesilicone binder (27 vs. 36% coating loss).

EXAMPLE 17

[0139] A carbon slurry was prepared according to the general procedureoutlined in Example 9 (3 um median particle size after milling) exceptthat SA-30 brand carbon from CarboChem was used instead of the Kreha PWcarbon. Additionally, 5% Tamol 165A dispersant (solids basis relative tocarbon solids) was added to the slurry instead of just 3%, and 15% M-50Esilicone binder (solids basis relative to carbon solids) was addedinstead of just 10%. Coating of radiator minicores was accomplished asdescribed in Example 9. However, prior to heat treating the samples inair at 300° C. for two hours, the samples were first heat-treated (i.e.,“carbonized”) at 200° C. in nitrogen for two hours. After both heattreatments, the samples were subjected to ultrasonic adhesion testing asdescribed in Example 9. Average coating loss was 16%. In this case,carbonizing the coating at 200° C. prior to high temperature exposure inair further improved the adhesion of the silicone-containing coating (16vs. 34% coating loss).

[0140] In general summary, the examples discussed above show thatbinders formed of silicone, in any form, such as polymers, sols orsilicates, or even combinations thereof, will effectively function, atthe desorption temperature ranges discussed above to adhere theactivated carbon to the substrate. In this regard the binder must meetat least two requirements. It has to adhere the activated carbon to thesubstrate so that the activated carbon particles are not stripped offthe substrate from the heated atmosphere stream flowing through thechannels. The binder also can not degrade at high temperatures so as tomaterially interfere with the porosity of the activated carbon andretard or hinder its ability to adsorb HC's VOC's.

[0141] As noted, the silicone containing activated carbon coating hasbeen applied to the substrate by a heat treatment in air at temperatureof about 300° C. which has produced a stable coating up to at leastabout 300° C. However, the coating can be heat treated at lessertemperatures and still exhibit stability at higher temperatures of atleast about 300° C.

[0142] D3) Regenerative Wheel Application for Activated Carbon.

[0143] It has been observed that coated wheels, when placed in service,will experience a loss in efficiency during a relatively short “breakin” period and thereafter will gradually decrease in efficiency reachinga relatively constant adsorption efficiency plateau. Reference can bemade to assignee's co-pending application Ser. No. 09/579,563, filed May26, 2000, for a detailed discussion of “road grime” causing wear of anMn0₂ ozone depleting catalyst applied to a vehicular radiator core toremove ozone from the atmosphere. (Note that ozone is deemed unhealthyat ambient trace concentrations of 120 parts per billion in contrast tothe 2-6 ppm range of VOC's present in the atmosphere.) Generally, wearoccurs due to deposition of airborne particulates less than 10 um insize. These airborne particulates typically contain elements such as C,N, O, Na, Mg, Al, Si, S, K, Cl and Ca. Activated carbon is well knownfor its use as a particulate filter. It would logically appear thatairborne particulates will eventually affect the porosity of theactivated carbon and thereby reduce its efficiency. This has not beenobserved because the efficiency of the activated carbon is retained. Ithas been suggested that the thermal disturbance inputted to the lightweight metal foil of the preferred embodiment in the shielded heatedregeneration zone coupled with the air flow could conceivably allowremoval of particulates including salts not firmly embedded in theactivated carbon. The removal is believed enhanced for counter currentflow application. In any event, the activated carbon, of the typespecified above, purifies the atmosphere of what can only be classifiedas unhealthy substances even though the matter is not deemed a VOC, HC,ozone or some other gaseous element subject to regulation bygovernmental agencies.

[0144] It should also be noted that while the main thrust of thisinvention is for a system to remove VOC's, particularly HC's, from theatmosphere (which are subsequently cleansed before disposal), example 3above shows that activated carbon is surprisingly effective to removeozone, O³, and, in fact, achieves rather high efficiencies in thisregard. The system is thus effective, not only as a VOC purifying systembut also an ozone depletion system. In this regard, the calorimetricsensor which functions as an OBD device to detect failure of heat wheelto remove VOC's may also function as OBD device to detect failure of thesystem to convert ozone to oxygen. As noted above, a correlation betweenVOC heat wheel life and ozone removal life can be empirically modeledand utilized. Alternatively, assuming that the VOC life of the activatedcarbon is less than that of the activated carbon to remove ozone (whichis believed likely because of the greater quantity of VOC treated, butwhich has not yet been established by tests), only the VOC's can bemonitored. A VOC failure means wheel replacement and thereforeregeneration of the ozone removal system.

E) Alternatives

[0145] The invention has been described with reference to a preferredembodiment capable of practically achieving cleansing of the atmosphereof VOC's including HC's as well as other matter with an activated carbonas an adsorbant. It is contemplated that a catalyst can also be providedin channels 70 with the activated carbon but not as a mixture or acomposition. For example, channels 70 could be coated with activatedcarbon over a half-channel length portion adjacent to entrance facesurface 31 and an ozone depleting substance, MnO², applied over ahalf-channel length portion adjacent to exit face surface 32. In thisexample, activated carbon and MnO² would not contact one another so thatheat wheel 30 could be viewed as being split into two heat wheels. Whileactivated carbon does remove ozone, as noted, coupling the activatedcarbon with an ozone depleting substance chosen for that purpose willenhance the overall efficiency of heat wheel 30 to dispose of ozone. Inthis instance, the ozone depleting substance, MnO², is capable ofwithstanding the regeneration temperatures of the application (150 to300° C.) without deterioration. In fact, the Mn0₂ destruction catalystwill have its life significantly extended due to thermal cleansing whencompared to current automotive applications where it is typicallyapplied to the radiator core. Additionally, calorimetric sensor 80 cansimultaneously function as an OBD sensor for the MnO² catalyst becauseit is believed that the life of the activated carbon to adsorb HC's willbe shorter than the life of the regenerated ozone depleting material.Thus detection of failure necessarily results in replacement of the heatwheel with a fresh ozone depleting substance.

[0146] This invention has determined that a regenerative wheel is thepreferred mechanism for effecting adsorption in an automotiveenvironment. In the preferred embodiment and as one aspect of theinvention, the wheel rotates because this is the simplest way to achieveregeneration while avoiding using of moving blades, baffles, fans,valves etc. which, as noted, is not desired. However, the invention canobviously function with a stationary wheel and moving atmospherestreams. Thus insofar as the invention is directed to an activatedcarbon adsorbent of the type described above, the invention is notnecessarily limited to a rotating wheel. Similarly, second positiondependent portion 66 of heat wheel 30 has been described as comprisingone “pie-shaped” or arcuate segment 60, but several could be employed.

[0147] Heat wheel 30 has been described and shown in the preferredembodiment, to be a “monolith” in a pancake type configuration havingchannels longitudinally extending the width or depth of the wheel.However, the invention is not necessarily limited to this wheel design.Other wheel configurations can be used. For example, a wheel in whichchannels 70 extended radially could be employed. Reference can he had toFIG. 10 which schematically illustrates such a wheel, and the samereference numerals used for describing heat wheel 30 depicted in FIGS. 2through 4 are used with reference to the heat wheel of FIG. 10. The FIG.10 heat wheel is not unique, but as can be seen from FIG. 10, this heatwheel design offers alternatives to the ducting disclosed in thepreferred embodiment. By radially positioning heat inlet and outletducts 42, 50 respectively, isolation of second position dependentportion 66 of the heat wheel could be enhanced providing duct sizing didnot create a significant pressure drop.

[0148] The invention has been described with reference to a preferredand alternative embodiments thereof. Modifications and alterations willbecome apparent to those skilled in the art upon reading andunderstanding the Detailed Description of the invention set forthherein. It is intended to include all such modifications and alterationsinsofar as they come with the scope of the present invention.

Having thus defined the invention, it is claimed: 1) A system forcleansing the atmosphere, including volatile organic compounds containedtherein, drawn into the engine compartment of a vehicle having aninternal combustion engine comprising: a) a heat wheel within the enginecompartment of said vehicle having a side defining an entrance facesurface and an opposite side defining an exit face surface; b) saidvehicle having a forward vehicular opening through which a stream ofatmosphere flows when the vehicle operates, said vehicular opening influid communication with a majority of the surface area of said entranceface surface of said heat wheel; c) a heat inlet duct having an entranceend in fluid communication with said vehicular opening and an exit endadjacent a portion of said entrance face surface of said heat wheel; d)a heat outlet duct having an entry end adjacent a portion of said exitface surface of said heat wheel and an exiting end in fluidcommunication with the emissions treating system of said vehicle, saidentry end of said heat outlet duct and said exit end of said heat inletduct generally aligned to be in registry with one another; e) a heattransfer mechanism in fluid communication with atmosphere flowing withinsaid heat inlet duct for raising the temperature thereof to a set value;f) a drive for rotating said heat wheel so that at any given time afirst position dependent portion of said heat wheel is in fluidcommunication with a first portion of said atmosphere stream drawnthrough said vehicular opening whereby said first atmosphere portionpasses through the first position dependent portion of said heat wheeland exhausts back to atmosphere while a second position dependentportion of said heat wheel is in fluid communication with a secondportion of said atmosphere stream drawn through said vehicular openinginto said heated inlet duct whereby said second atmosphere portion isheated by said heat transfer mechanism and exhausted to said heat outletduct after passing through said second position dependent portion ofsaid heat wheel; and, g) said heat wheel having a plurality of channelsextending from said entrance face of said heat wheel to said exit facesurface thereof, each channel having surfaces coated with an adsorberselected from the group consisting of zeolite, active carbon, carbonmolecular sieves, mesapore solids and micropore solids whereby saidvolatile organic compounds are adsorbed in said first position dependentportion of said wheel and desorbed in said second position dependentportion of said wheel. 2) The system of claim 1 wherein each channel isbounded by configured walls extending from said entrance face surface tosaid exit end face of said heat wheel, each wall of inner channelsforming on opposite sides thereof portions of adjacent channels wherebya honeycomb channel pattern extends through said heat wheel. 3) Thesystem of claim 2 wherein said adsorber is activated carbon havingmicropore porosity, a coating density greater than 0.5 g/in³ and aparticle size less than about 25 microns whereby ozone as well as saidvolatile organic compounds are removed from said atmosphere atpercentages higher than at least about 30 percent and said highertemperatures are in the range of approximately 150 to 300° C. and saidheat transfer mechanism using sensible exhaust gas heat to heat saidatmosphere stream portion in said heat inlet duct to said highertemperatures. 4) The system of claim 3 where said activated carbon has aparticle size less than about 5 microns and said adsorption efficienciesare approximately 50% or higher. 5) The system of claim 3 wherein saidwalls of said heat wheel channels are formed from material selected fromthe group consisting of metals, ceramics and plastics, said wallsforming a substrate for receiving particles of said activated carbon. 6)The system of claim 5 wherein said activated carbon is bound to saidsubstrate as a coating by a binder said binder substantially includingsilicone in any form including polymeric silicones, silica sols andsilicates, said binder being sufficient to withstand said temperaturesin said second position dependent portion of said heat wheel. 7) Thesystem of claim 2 wherein the configuration of said second positiondependent portion of said heat wheel, said exit end of said heat inletduct and said entry end of said heat outlet duct is substantiallydefined as an arcuate segment extending between radial lines forming anincluded angle anywhere between 10 to 45°, and said radial lines betweenadjacent heat wheel segments are spaced from one another to define aradial gap between adjacent heat wheel segments. 8) The system of claim7 wherein the configuration of said first position dependent portion ofsaid heat wheel is substantially defined as at least one arcuate segmentextending between radial lines forming an included angle anywherebetween 315 to 350°. 9) The system of claim 8 wherein said exit end ofsaid heat inlet duct confronts one face surface of said heat wheel whilesaid vehicle opening confronts the opposite face surface of said heatwheel whereby said atmosphere flow through said heat wheel in saidsecond position dependent portion is counter to the direction of saidatmosphere flow through said heat wheel in said first position dependentportion. 10) The system of claim 7 wherein said drive includes a motorand a microprocessor having a programmed routine for actuating saidmotor to rotate said heat wheel in a predetermined manner. 11) Thesystem of claim 10 wherein said heat wheel is physically formed as acylinder comprising axially extending arcuate segments spanning anincluded angle substantially equal to said included angle of said exitend of said heat inlet duct and said entry end of said heat outlet ductand said programmed routine causes said motor to rotate said wheel atangular increments equal to said included angle of said arcuatesegments. 12) The system of claim 11 wherein said programmed routinecauses said drive to rotatably index said wheel at a set time periodmodeled from the time it takes to desorb a wheel segment which has beensubstantially saturated with adsorbed volatile organic compounds. 13)The system of claim 11 further including a hydrocarbon sensor positionedadjacent an exit face surface of said heat wheel whereat said atmosphereexits said heat wheel, said routine effective to periodically sample thehydrocarbon readings of said sensor to determine a change in sensedhydrocarbon beyond a set limit whereat said microprocessor causes saidheal wheel to index a segment. 14) The system of claim 13 wherein saidsensor is a calorimetric sensor positioned in said exit heat duct andsaid routine causes said heat wheel to index when said sensor fails todetect the presence of hydrocarbons. 15) The system of claim 13 furtherincluding an alarm in the cabin of said vehicle, said routine effectiveto cause said alarm to actuate indicating a replacement of said wheelwhen said routine determines that said sensor readings do notsubstantially change over a set time period. 16) The system of claim 3further including an ozone depleting catalyst at one end of saidchannels adjacent the side of said heat wheel whereat said atmosphereexits said heat wheel, said activated carbon deposited at the oppositeend of said channels adjacent the side of said heat wheel whereat saidatmosphere enters said heat wheel. 17) The system of claim 16 whereinsaid ozone depleting catalyst is MnO². 18) The system of claim 3 whereinsaid vehicle has an exhaust system in fluid communication with anexhaust manifold on said engine, said exhaust system having a catalyticconverter for purifying emissions from exhaust gases emitted by saidengine, said portion of said inlet heat duct in heat transfer relationto said exhaust gases including a gas-to-gas heat exchanger in fluidcommunication with said exhaust gases and positioned within said secondinlet duct. 19) The system of claim 3 wherein said exiting end of saidheat outlet duct is in fluid communication with an intake manifold ofsaid engine whereby said engine treats said VOC emissions prior todischarging the treated VOC emissions to a catalytic exhaust gaspurifying system. 20) The system of claim 3 wherein said vehicle has anexhaust system including a catalytic converter and said exiting end ofsaid heat outlet duct is in fluid communication with said exhaust systemupstream of said catalytic converter. 21) The system of claim 20 whereinsaid exiting end of said heat outlet duct is also in fluid communicationwith an intake manifold on said vehicle. 22) The system of claim 3wherein said heat wheel is an annular cylinder, said heat wheel channelsextend radially through said heat wheel, and said heat inlet duct ispositioned to extend radially outside of and about said heat wheel whilesaid heat outlet duct is positioned radially inside of said heat wheelor vice-versa. 23) The system of claim 3 wherein said engine has anexhaust manifold and said heat inlet duct in heat transfer relationshipwith the sensible heat of said exhaust gases includes a portion of saidheat inlet duct formed contiguous with a portion of said exhaustmanifold whereby said atmosphere stream portion flowing in said heatoutlet duct is heated by contact with said exhaust manifold. 24) Thesystem of claim 6 wherein said coating results from heating a slurry ofactivated carbon with a binder containing silicone in any form includingpolymeric silicones, silica sols and silicates at elevated temperaturessufficient to stabilize said coating at temperatures up to at leastabout 300° C. 25) The system of claim 24 wherein said elevatedtemperature is at least about 300° C. and said coating results from asilicone latex binder in said slurry heated to an initial temperature inthe presence of an inert gas. 26) The system of claim 25 wherein saidinert gas is nitrogen and said initial temperature is less than saidelevated temperature. 27) A system for cleansing the atmosphere,including volatile organic compounds contained therein, drawn into theengine compartment of a vehicle having an internal combustion enginecomprising: a) a rotatable heat wheel having channels extendingtherethrough from one side to an opposite side of said heat wheel, saidchannels having a coating of activated carbon on the surface thereof,said activated carbon having micropore porosity, a coating densitygreater than 0.5 g/in³ and a mean particle size less than about 25microns; b) means for directing a stream of atmosphere at engine cabinambient temperature through a first position dependent portion of saidheat wheel on one side of said heat wheel; c) means for directing aheated stream of atmosphere through a second position dependent portionof said heat wheel at temperatures within the range of approximately150-300° C.; and d) means for rotating said heat wheel. 28) The systemof claim 27 wherein said particle size is not greater than about 5microns. 29) The system of claim 28 wherein said channels are formed ofwalls in a honeycomb pattern where opposite surfaces of any given wallform portions of adjacent channels, said walls of said heat wheelchannels are formed from material selected from the group consisting ofmetals, ceramics and plastics, said walls forming a substrate forreceiving particles of said activated carbon. 30) The system of claim 25wherein said activated carbon is bound to said substrate by a binder,said binder substantially including silicone in any form, said binderbeing sufficient to withstand said temperatures in said second positiondependent portion of said heat wheel. 31) The system of claim 30 whereinsaid means for directing a heated stream of atmosphere includes meansfor directing the sensible heat of said exhaust gases through a portionof an atmosphere stream to heat said atmosphere stream portion to saidtemperature range of from 150 to 300° C. 32) The system of claim 31further including a heat outlet duct on the opposite side of said heatwheel from the side whereat said means for directing a heated stream ofatmosphere enters said heat wheel, said heat outlet duct in fluidcommunication with an intake manifold of said engine and a hydrocarbonsensor in said heat outlet duct for sensing the presence of hydrocarbonsin the atmosphere in said heat outlet duct, said means for rotating saidheat wheel including a microprocessor and a programmed routine effectiveto control the rotation of said heat wheel as a function of thehydrocarbons sensed by said sensor. 33) The system of claim 32 whereinsaid sensor is a calorimetric sensor having an oxidizing catalystdeposited on a surface thereof over which said atmosphere passes, a noncatalyzed reference surface over which said atmosphere also passes and aheater for heating both catalyzed and non catalyzed surfaces todetermine the presence or absence of hydrocarbons. 34) The system ofclaim 27 wherein said coating results from heating a slurry of activatedcarbon with a binder containing silicone in any form including polymericsilicones, silica sols and silicates at elevated temperatures sufficientto stabilize said coating at temperatures up to at least about 300° C.35) The system of claim 34 wherein said elevated temperature is at leastabout 300° C. and said coating results from a silicone latex binder insaid slurry heated to an initial temperature in the presence of an inertgas. 36) The system of claim 35 wherein said inert gas is nitrogen andsaid initial temperature is less than said elevated temperature. 37) Asystem for cleansing the atmosphere of volatile organic compoundscontained therein that is drawn into the engine compartment of a vehiclehaving an internal combustion engine comprising: a) a rotatable heatwheel having channels extending therethrough from one side to anopposite side of said heat wheel, said channels coated with an adsorberselected from the group consisting of zeolites, cordierites, activecarbons, carbon molecular sieves, mesapore solids and micropore solids;b) means for directing a stream of atmosphere at engine cabin ambienttemperature through a first position dependent portion of said heatwheel on one side of said heat wheel; c) means for directing a heatedstream of atmosphere through a second position dependent portion of saidheat wheel; d) means for directing the heated stream of atmosphere afterpassing through said heat wheel to an exhaust emission system of saidengine, said directing means including a heat outlet duct; e) means forrotating said heat wheel, and f) a sensor in said heat outlet duct fordetermining the presence of hydrocarbon in the heated atmosphere wherebythe effectiveness of said heat wheel is determined. 38) The system ofclaim 37 wherein said sensor is a calorimetric sensor having anoxidizing catalyst deposited on a surface thereof over which saidatmosphere passes, a non catalyzed reference surface over which saidatmosphere also passes and a heater for heating both catalyzed and noncatalyzed surfaces to determine the presence or absence of hydrocarbons.39) The system of claim 38 wherein said means for rotating said heatwheel includes a microprocessor and a programmed routine effective tocontrol the rotation of said heat wheel as a function of thehydrocarbons sensed by said sensor. 40) The system of claim 39 whereinsaid routine causes said drive means to rotate said wheel through afixed, included angle when said sensor fails to detect the presence ofhydrocarbons for a set time period. 41) The system of claim 40 whereinsaid system includes a warning indicator in a cabin of said vehicle,said warning indicator actuated by said microprocessor, said routinedetermining the effectiveness of said adsorber to desorb said volatileorganic compounds and actuating said warning indicator when theeffectiveness of said adsorber drops below a preset level whereby theeffectiveness of the system to remove volatile organic compounds ismonitored. 42) The system of claim 41 wherein said adsorber is activatedcarbon having micropore porosity, a coating density greater than 0.5g/in³ for substrates selected from the group consisting of metals,ceramics and plastics and a particle size less than about 10 micronswhereby ozone as well as said volatile organic compounds are removedfrom said atmosphere at conversion percentages higher than at leastabout 50 percent whereby the effectiveness of the system to monitor theeffectiveness of the system to remove volatile organic compounds andozone is monitored through one sensor. 43) A method for cleansing theatmosphere by a vehicle powered by an internal combustion enginecomprising the steps of: a) drawing a first stream of atmosphere intothe engine compartment of a vehicle by means of a fan and/or the motionof the vehicle, said first atmosphere steam being at ambient enginecabin temperature; b) drawing a second stream of atmosphere eitherseparately from said first stream or split from said first stream intosaid second stream by means of a fan and/or the motion of the vehicle;c) heating said second atmosphere stream by sensible heat from exhaustgases produced by said engine to temperatures in the range ofapproximately 150 to 300° C.; d) providing a heat wheel having channelsextending therethrough from one side of said heat wheel to the oppositeside of said heat wheel; said channels having as a coating thereonactivated carbon of a micropore porosity, said carbon having a densityof at least 0.5 g/in³ and a mean particle size not greater than 25microns; e) passing said first stream of atmosphere through channelsoccupying, at any given time, a first position dependent portion of saidheat wheel to adsorb volatile organic compounds contained in saidatmosphere; f) passing said second stream of heated atmosphere throughchannels occupying, at any given time, a second position dependentportion of said heat wheel to desorb volatile organic compoundscontained in said channels; g) directing said second stream of heatedatmosphere with volatile organic compounds desorbed from said wheel tothe gaseous emission treating system of said vehicle; and, h) rotatingsaid wheel so that before the channels in said first position dependentportion of said heat wheel become saturated with volatile organiccompounds they are rotated into a position whereat the channels becomechannels forming the second position dependent portion of said heatwheel while the desorbed channels formerly forming the second positiondependent portion of said heat wheel are rotated into a position whereatthe channels become part of the channels forming said first positiondependent portion of said heat wheel. 44) The method of claim 43 whereinsaid heat wheel is rotated as a function of the time it takes to desorbthe volatile organic compounds in said second position dependent portionof said heat wheel. 45) The method of claim 44 wherein said heating ofsaid second atmosphere stream occurs by passing said second stream overan exhaust manifold of said engine. 46) The method of claim 45 furtherincluding the step of sensing the hydrocarbons in said second atmospherestream after said second atmosphere stream has passed through saidsecond position dependent portion of said heat wheel and rotating saidheat wheel through a set, included angle when hydrocarbons are no longersensed as being present for a set time period. 47) The method of claim46 further including the step of providing an alarm in an operator cabinof said vehicle and actuating said alarm if hydrocarbons are notinitially sensed upon rotation of said heat wheel. 48) The method ofclaim 47 wherein said sensing step is accomplished by a calorimetricsensor having a heated catalyzed surface and a heated non-catalyzedsurface over which a slip stream of said second atmosphere stream ispassed after leaving said heat wheel. 49) The method of claim 48 whereinthe mean activated carbon particle size is less than 25 microns and saidactivated carbon including the step of reducing ozone in addition toadsorbing said volatile organic compounds so that the step ofregenerating said activated carbon upon heating not only regeneratingthe ability of said activated carbon to adsorb volatile organiccompounds but also regenerating the ability of said activated carbon tocatalyze ozone reducing reactions to O². 50) The method of claim 49wherein the step of directing said second atmosphere stream to saidvehicle's emission system after passing through said heat wheel occursby initially directing said second atmosphere stream to an intakemanifold of said engine. 51) The method of claim 50 wherein said wheelis divided into a plurality of arcuate segments of an included angleextending between radial lines defining the edge of each segment, saidwheel having a radial space between radial edge lines of each segment sothat as each segment is rotated into said second position dependentportion, the heat from the segment in said second position dependentportion tending to be isolated from the segments in said first positiondependent portion. 52) The method of claim 51 wherein said rotationoccurs by sensing the temperature of said exhaust gases and indexingsaid wheel before heat from said second position dependent portion ofsaid wheel materially affects the temperature of said segments in saidfirst dependent portion of said heat wheel provided that saidhydrocarbons sensed in said heat outlet duct have dropped below a setvalue. 53) The method of claim 43 further including the step of adheringsaid activated carbon as a coating on said channels by providing aslurry of said activated carbon to which is added a silicone binder inany form and heating said slurry applied to said channels at elevatedtemperatures in the presence of air to stabilize said coating attemperatures at least up to 300° C. 54) The method of claim 53 whereinsaid silicone binder is a silicone latex binder and said slurry isinitially heated in only the presence of an inert gas at an initialtemperature. 55) The method of claim 54 wherein said inert gas isnitrogen and said slurry is initially heated to temperatures less thansaid elevated temperature and said elevated temperature is approximately300° C. 56) A system for cleansing the atmosphere of volatile organiccompounds contained therein that is drawn in to the engine compartmentof a vehicle having an internal combustion engine comprising: a) arotatable heat wheel having portions containing channels through whichan atmosphere stream and a heated atmosphere stream pass therethrough,said heat wheel having an adsorber composition coated on said channels;b) a motor for rotating said wheel so that various portions of saidwheel are sequentially heated by said heated atmosphere stream to desorbvolatile organic compounds adsorbed from said atmosphere stream; c) asensor for sensing the presence of hydrocarbons in said heatedatmosphere stream after passing through said wheel; and, d) an alarmactuated by said sensor when said sensor detects that the wheel has agedto a condition whereat said wheel is not able to adsorb volatile organiccompounds above a set limit. 57) The system of claim 56 wherein saidsensor additionally determines actuation of said motor for rotating saidwheel. 58) The system of claim 57 wherein said hydrocarbon sensor is acalorimetric sensor. 59) The system of claim 58 wherein said adsorber isactivated carbon.